Make #[used(linker)] the default on ELF too - #140872
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r? @nnethercote rustbot has assigned @nnethercote. Use |
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Some changes occurred in compiler/rustc_codegen_ssa Some changes occurred in compiler/rustc_codegen_ssa/src/codegen_attrs.rs |
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cg_clif currently treats |
This was referenced May 9, 2025
Contributor
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Looks ok to me, but as this is the first I've heard of these attributes, I will run it past the person who first suggested them: r? @nikic |
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This generally sounds reasonable to me in the interest of having consistent behavior across platforms. Some questions:
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symbols.o only ensures that the object file containing the symbol is pulled in from an archive. It does nothing to stop
I want to guarantee the |
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It would at least remove the main reason why we introduced |
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Author
SHF_GNU_RETAIN is a lot newer than I thought. It was only introduced in 2021 with binutils 2.36. I guess that means we can't make it a hard guarantee for now. We can stop passing |
Noratrieb
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May 24, 2025
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☔ The latest upstream changes (presumably #141518) made this pull request unmergeable. Please resolve the merge conflicts. |
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I did some investigation on the history of Originally, the previously existing C-equivalent of It was then discovered that this behavior broke projects, like the Linux kernel (https://gcc.gnu.org/pipermail/gcc-patches/2021-February/565337.html). The reason for that was that they already used So what does that mean for Rust? Since we always use the equivalent of I've opened #141750 to see whether it's possible to warn about the potential miscompiles with gold. |
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@nikic Do you have additional concerns regarding the I suppose that we don't need to concern ourselves with gold anymore, as with #141748 we warn about its usage, and it has been marked as deprecated. |
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I guess if we're mainly targeting the linkme use case, it should be fine, because the overlap of "enables start/stop GC by default" and "does not support SHF_RETAIN" should be empty (right?) More widely, we may hit issues with ancient binutils versions used by the undead cross-rs project... |
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This is fine from my side.
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I'm not 100% sure, but it seems like so. BFD and gold still use the conservative behavior, and LLD started using start/stop GC from version 13, where it also started supporting SHF_GNU_RETAIN, AFAIK. |
#[used] currently is an alias for #[used(linker)] on all platforms except ELF based ones where it is an alias for #[used(compiler)]. The latter has surprising behavior and the LLVM LangRef explicitly states that it "should only be used in rare circumstances, and should not be exposed to source languages." The reason #[used] still was an alias to #[used(compiler)] on ELF is because the gold linker has issues with it. Luckily gold has been deprecated with GCC 15 and seems to be unable to bootstrap rustc anyway. As such we shouldn't really care about supporting gold.
ojeda
added a commit
to ojeda/linux
that referenced
this pull request
Jul 12, 2025
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1] treat
`#[used]` as `#[used(linker)]` instead of `#[used(compiler)]` for our
targets. This means that the retain section flag (`R`, `SHF_GNU_RETAIN`)
will be used and that they will be marked as `unique` too, with different
IDs. In turn, that means we end up with undefined references that did
not get discarded and that multiple `.modinfo` sections are generated,
which confuse tooling like `modpost` because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda
added a commit
to ojeda/linux
that referenced
this pull request
Jul 12, 2025
… 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
intel-lab-lkp
pushed a commit
to intel-lab-lkp/linux
that referenced
this pull request
Jul 12, 2025
… 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda
added a commit
to Rust-for-Linux/linux
that referenced
this pull request
Jul 14, 2025
… 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda
added a commit
to Rust-for-Linux/linux
that referenced
this pull request
Jul 14, 2025
… 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda
added a commit
to Rust-for-Linux/linux
that referenced
this pull request
Jul 14, 2025
… 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda
added a commit
to Rust-for-Linux/linux
that referenced
this pull request
Jul 14, 2025
… 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda
added a commit
to ojeda/linux
that referenced
this pull request
Jul 21, 2025
… 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
(cherry picked from commit 7498159)
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
firmware-kpd Bot
pushed a commit
to linux-kdevops/linux-firmware-kpd
that referenced
this pull request
Jul 23, 2025
… 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:
kernel...-cgu.0:(.text....+0x116): undefined reference to
`rust_helper_kunit_get_current_test'
Moreover, tooling like `modpost` gets confused:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o
The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.
Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].
The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].
Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.
Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: rust-lang/rust#140872 [1]
Link: rust-lang/rust#93798 [2]
Link: rust-lang/rust#91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
(cherry picked from commit 7498159)
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Whissi
pushed a commit
to Whissi/linux-stable
that referenced
this pull request
Jul 24, 2025
… 1.89.0 commit 7498159 upstream. Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails to build the `rusttest` target due to undefined references such as: kernel...-cgu.0:(.text....+0x116): undefined reference to `rust_helper_kunit_get_current_test' Moreover, tooling like `modpost` gets confused: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o The reason behind both issues is that the Rust compiler will now [1] treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]` for our targets. This means that the retain section flag (`R`, `SHF_GNU_RETAIN`) will be used and that they will be marked as `unique` too, with different IDs. In turn, that means we end up with undefined references that did not get discarded in `rusttest` and that multiple `.modinfo` sections are generated, which confuse tooling like `modpost` because they only expect one. Thus start using `#[used(compiler)]` to keep the previous behavior and to be explicit about what we want. Sadly, it is an unstable feature (`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good news is that it has been available for a long time (Rust >= 1.60) [3]. The changes should also be fine for previous Rust versions, since they behave the same way as before [4]. Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]` since those still behave like `#[used(compiler)]`, but of course it is not really what we want to express, and it requires other changes to avoid symbol conflicts. Cc: David Wood <david@davidtw.co> Cc: Wesley Wiser <wwiser@gmail.com> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: rust-lang/rust#140872 [1] Link: rust-lang/rust#93798 [2] Link: rust-lang/rust#91504 [3] Link: https://godbolt.org/z/sxzWTMfzW [4] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
gregkh
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Jul 24, 2025
… 1.89.0 commit 7498159 upstream. Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails to build the `rusttest` target due to undefined references such as: kernel...-cgu.0:(.text....+0x116): undefined reference to `rust_helper_kunit_get_current_test' Moreover, tooling like `modpost` gets confused: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o The reason behind both issues is that the Rust compiler will now [1] treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]` for our targets. This means that the retain section flag (`R`, `SHF_GNU_RETAIN`) will be used and that they will be marked as `unique` too, with different IDs. In turn, that means we end up with undefined references that did not get discarded in `rusttest` and that multiple `.modinfo` sections are generated, which confuse tooling like `modpost` because they only expect one. Thus start using `#[used(compiler)]` to keep the previous behavior and to be explicit about what we want. Sadly, it is an unstable feature (`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good news is that it has been available for a long time (Rust >= 1.60) [3]. The changes should also be fine for previous Rust versions, since they behave the same way as before [4]. Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]` since those still behave like `#[used(compiler)]`, but of course it is not really what we want to express, and it requires other changes to avoid symbol conflicts. Cc: David Wood <david@davidtw.co> Cc: Wesley Wiser <wwiser@gmail.com> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: rust-lang/rust#140872 [1] Link: rust-lang/rust#93798 [2] Link: rust-lang/rust#91504 [3] Link: https://godbolt.org/z/sxzWTMfzW [4] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
opsiff
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Jul 27, 2025
… 1.89.0 commit 7498159 upstream. Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails to build the `rusttest` target due to undefined references such as: kernel...-cgu.0:(.text....+0x116): undefined reference to `rust_helper_kunit_get_current_test' Moreover, tooling like `modpost` gets confused: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o The reason behind both issues is that the Rust compiler will now [1] treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]` for our targets. This means that the retain section flag (`R`, `SHF_GNU_RETAIN`) will be used and that they will be marked as `unique` too, with different IDs. In turn, that means we end up with undefined references that did not get discarded in `rusttest` and that multiple `.modinfo` sections are generated, which confuse tooling like `modpost` because they only expect one. Thus start using `#[used(compiler)]` to keep the previous behavior and to be explicit about what we want. Sadly, it is an unstable feature (`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good news is that it has been available for a long time (Rust >= 1.60) [3]. The changes should also be fine for previous Rust versions, since they behave the same way as before [4]. Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]` since those still behave like `#[used(compiler)]`, but of course it is not really what we want to express, and it requires other changes to avoid symbol conflicts. Cc: David Wood <david@davidtw.co> Cc: Wesley Wiser <wwiser@gmail.com> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: rust-lang/rust#140872 [1] Link: rust-lang/rust#93798 [2] Link: rust-lang/rust#91504 [3] Link: https://godbolt.org/z/sxzWTMfzW [4] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit d9ebd928288bb82df8efeb3a34f2cd31883f440e)
taraant
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Jul 28, 2025
… 1.89.0 commit 7498159 upstream. Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails to build the `rusttest` target due to undefined references such as: kernel...-cgu.0:(.text....+0x116): undefined reference to `rust_helper_kunit_get_current_test' Moreover, tooling like `modpost` gets confused: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o The reason behind both issues is that the Rust compiler will now [1] treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]` for our targets. This means that the retain section flag (`R`, `SHF_GNU_RETAIN`) will be used and that they will be marked as `unique` too, with different IDs. In turn, that means we end up with undefined references that did not get discarded in `rusttest` and that multiple `.modinfo` sections are generated, which confuse tooling like `modpost` because they only expect one. Thus start using `#[used(compiler)]` to keep the previous behavior and to be explicit about what we want. Sadly, it is an unstable feature (`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good news is that it has been available for a long time (Rust >= 1.60) [3]. The changes should also be fine for previous Rust versions, since they behave the same way as before [4]. Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]` since those still behave like `#[used(compiler)]`, but of course it is not really what we want to express, and it requires other changes to avoid symbol conflicts. Cc: David Wood <david@davidtw.co> Cc: Wesley Wiser <wwiser@gmail.com> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: rust-lang/rust#140872 [1] Link: rust-lang/rust#93798 [2] Link: rust-lang/rust#91504 [3] Link: https://godbolt.org/z/sxzWTMfzW [4] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
oraclelinuxkernel
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Aug 8, 2025
… 1.89.0 commit 7498159 upstream. Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails to build the `rusttest` target due to undefined references such as: kernel...-cgu.0:(.text....+0x116): undefined reference to `rust_helper_kunit_get_current_test' Moreover, tooling like `modpost` gets confused: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o The reason behind both issues is that the Rust compiler will now [1] treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]` for our targets. This means that the retain section flag (`R`, `SHF_GNU_RETAIN`) will be used and that they will be marked as `unique` too, with different IDs. In turn, that means we end up with undefined references that did not get discarded in `rusttest` and that multiple `.modinfo` sections are generated, which confuse tooling like `modpost` because they only expect one. Thus start using `#[used(compiler)]` to keep the previous behavior and to be explicit about what we want. Sadly, it is an unstable feature (`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good news is that it has been available for a long time (Rust >= 1.60) [3]. The changes should also be fine for previous Rust versions, since they behave the same way as before [4]. Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]` since those still behave like `#[used(compiler)]`, but of course it is not really what we want to express, and it requires other changes to avoid symbol conflicts. Cc: David Wood <david@davidtw.co> Cc: Wesley Wiser <wwiser@gmail.com> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: rust-lang/rust#140872 [1] Link: rust-lang/rust#93798 [2] Link: rust-lang/rust#91504 [3] Link: https://godbolt.org/z/sxzWTMfzW [4] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit d9ebd928288bb82df8efeb3a34f2cd31883f440e) Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
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iximeow
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Sep 28, 2025
illumos' `ld` does not support a flag like either SHF_GNU_RETAIN or SHF_SUNW_NODISCARD, so there is no way to communicate `#[used(linker)]` for that target. Setting `USED_LINKER` to try results in LLVM setting SHF_SUNW_NODISCARD for Solaris-like targets, which is an unknown section header flag for illumos `ld` and prevents sections from being merged that otherwise would. As a motivating example, the `inventory` crate produces `#[used]` items to merge into `.init_array`. Because those items have an unknown section header flag they are not merged with the default `.init_array` with `frame_dummy`, and end up never executed. Downgrading `#[used]` to `#[used(compiler)]` on illumos keeps so-attributed items as preserved as they had been before rust-lang#140872. As was the case before that change, because rustc passes `-z ignore` to illumos `ld`, it's possible that `used` sections are GC'd at link time. rust-lang#146169 describes this unfortunate circumstance.
iximeow
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Oct 3, 2025
illumos' `ld` does not support a flag like either SHF_GNU_RETAIN or SHF_SUNW_NODISCARD, so there is no way to communicate `#[used(linker)]` for that target. Setting `USED_LINKER` to try results in LLVM setting SHF_SUNW_NODISCARD for Solaris-like targets, which is an unknown section header flag for illumos `ld` and prevents sections from being merged that otherwise would. As a motivating example, the `inventory` crate produces `#[used]` items to merge into `.init_array`. Because those items have an unknown section header flag they are not merged with the default `.init_array` with `frame_dummy`, and end up never executed. Downgrading `#[used]` to `#[used(compiler)]` on illumos keeps so-attributed items as preserved as they had been before rust-lang#140872. As was the case before that change, because rustc passes `-z ignore` to illumos `ld`, it's possible that `used` sections are GC'd at link time. rust-lang#146169 describes this unfortunate circumstance.
Zalathar
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Oct 4, 2025
…oratrieb interpret `#[used]` as `#[used(compiler)]` on illumos helps rust-lang#146169 not be as painful: fixes the illumos regression in rust-lang#140872, but `#[used(linker)]` is still erroneous on illumos generally. illumos' `ld` does not support a flag like either SHF_GNU_RETAIN or SHF_SUNW_NODISCARD, so there is no way to communicate `#[used(linker)]` for that target. Setting `USED_LINKER` to try results in LLVM setting SHF_SUNW_NODISCARD for Solaris-like targets, which is an unknown section header flag for illumos `ld` and prevents sections from being merged that otherwise would. As a motivating example, the `inventory` crate produces `#[used]` items to merge into `.init_array`. Because those items have an unknown section header flag they are not merged with the default `.init_array` with `frame_dummy`, and end up never executed. Downgrading `#[used]` to `#[used(compiler)]` on illumos keeps so-attributed items as preserved as they had been before rust-lang#140872. As was the case before that change, because rustc passes `-z ignore` to illumos `ld`, it's possible that `used` sections are GC'd at link time. rust-lang#146169 describes this unfortunate circumstance. ---- as it turns out, `tests/ui/attributes/used_with_archive.rs` had broken on `x86_64-unknown-illumos`, and this patch fixes it. the trials and tribulations of tier 2 :( r? `@Noratrieb` probably?
matthiaskrgr
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Oct 4, 2025
…oratrieb interpret `#[used]` as `#[used(compiler)]` on illumos helps rust-lang#146169 not be as painful: fixes the illumos regression in rust-lang#140872, but `#[used(linker)]` is still erroneous on illumos generally. illumos' `ld` does not support a flag like either SHF_GNU_RETAIN or SHF_SUNW_NODISCARD, so there is no way to communicate `#[used(linker)]` for that target. Setting `USED_LINKER` to try results in LLVM setting SHF_SUNW_NODISCARD for Solaris-like targets, which is an unknown section header flag for illumos `ld` and prevents sections from being merged that otherwise would. As a motivating example, the `inventory` crate produces `#[used]` items to merge into `.init_array`. Because those items have an unknown section header flag they are not merged with the default `.init_array` with `frame_dummy`, and end up never executed. Downgrading `#[used]` to `#[used(compiler)]` on illumos keeps so-attributed items as preserved as they had been before rust-lang#140872. As was the case before that change, because rustc passes `-z ignore` to illumos `ld`, it's possible that `used` sections are GC'd at link time. rust-lang#146169 describes this unfortunate circumstance. ---- as it turns out, `tests/ui/attributes/used_with_archive.rs` had broken on `x86_64-unknown-illumos`, and this patch fixes it. the trials and tribulations of tier 2 :( r? ``@Noratrieb`` probably?
matthiaskrgr
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Oct 4, 2025
…oratrieb interpret `#[used]` as `#[used(compiler)]` on illumos helps rust-lang#146169 not be as painful: fixes the illumos regression in rust-lang#140872, but `#[used(linker)]` is still erroneous on illumos generally. illumos' `ld` does not support a flag like either SHF_GNU_RETAIN or SHF_SUNW_NODISCARD, so there is no way to communicate `#[used(linker)]` for that target. Setting `USED_LINKER` to try results in LLVM setting SHF_SUNW_NODISCARD for Solaris-like targets, which is an unknown section header flag for illumos `ld` and prevents sections from being merged that otherwise would. As a motivating example, the `inventory` crate produces `#[used]` items to merge into `.init_array`. Because those items have an unknown section header flag they are not merged with the default `.init_array` with `frame_dummy`, and end up never executed. Downgrading `#[used]` to `#[used(compiler)]` on illumos keeps so-attributed items as preserved as they had been before rust-lang#140872. As was the case before that change, because rustc passes `-z ignore` to illumos `ld`, it's possible that `used` sections are GC'd at link time. rust-lang#146169 describes this unfortunate circumstance. ---- as it turns out, `tests/ui/attributes/used_with_archive.rs` had broken on `x86_64-unknown-illumos`, and this patch fixes it. the trials and tribulations of tier 2 :( r? ```@Noratrieb``` probably?
matthiaskrgr
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Oct 4, 2025
…oratrieb interpret `#[used]` as `#[used(compiler)]` on illumos helps rust-lang#146169 not be as painful: fixes the illumos regression in rust-lang#140872, but `#[used(linker)]` is still erroneous on illumos generally. illumos' `ld` does not support a flag like either SHF_GNU_RETAIN or SHF_SUNW_NODISCARD, so there is no way to communicate `#[used(linker)]` for that target. Setting `USED_LINKER` to try results in LLVM setting SHF_SUNW_NODISCARD for Solaris-like targets, which is an unknown section header flag for illumos `ld` and prevents sections from being merged that otherwise would. As a motivating example, the `inventory` crate produces `#[used]` items to merge into `.init_array`. Because those items have an unknown section header flag they are not merged with the default `.init_array` with `frame_dummy`, and end up never executed. Downgrading `#[used]` to `#[used(compiler)]` on illumos keeps so-attributed items as preserved as they had been before rust-lang#140872. As was the case before that change, because rustc passes `-z ignore` to illumos `ld`, it's possible that `used` sections are GC'd at link time. rust-lang#146169 describes this unfortunate circumstance. ---- as it turns out, `tests/ui/attributes/used_with_archive.rs` had broken on `x86_64-unknown-illumos`, and this patch fixes it. the trials and tribulations of tier 2 :( r? ````@Noratrieb```` probably?
rust-timer
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Oct 4, 2025
Rollup merge of #147117 - iximeow:ixi/illumos-used-attr, r=Noratrieb interpret `#[used]` as `#[used(compiler)]` on illumos helps #146169 not be as painful: fixes the illumos regression in #140872, but `#[used(linker)]` is still erroneous on illumos generally. illumos' `ld` does not support a flag like either SHF_GNU_RETAIN or SHF_SUNW_NODISCARD, so there is no way to communicate `#[used(linker)]` for that target. Setting `USED_LINKER` to try results in LLVM setting SHF_SUNW_NODISCARD for Solaris-like targets, which is an unknown section header flag for illumos `ld` and prevents sections from being merged that otherwise would. As a motivating example, the `inventory` crate produces `#[used]` items to merge into `.init_array`. Because those items have an unknown section header flag they are not merged with the default `.init_array` with `frame_dummy`, and end up never executed. Downgrading `#[used]` to `#[used(compiler)]` on illumos keeps so-attributed items as preserved as they had been before #140872. As was the case before that change, because rustc passes `-z ignore` to illumos `ld`, it's possible that `used` sections are GC'd at link time. #146169 describes this unfortunate circumstance. ---- as it turns out, `tests/ui/attributes/used_with_archive.rs` had broken on `x86_64-unknown-illumos`, and this patch fixes it. the trials and tribulations of tier 2 :( r? ````@Noratrieb```` probably?
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#[used]currently is an alias for#[used(linker)]on all platforms except ELF based ones where it is an alias for#[used(compiler)]. The latter has surprising behavior and the LLVM LangRef explicitly states that it "should only be used in rare circumstances, and should not be exposed to source languages." 1The reason
#[used]still was an alias to#[used(compiler)]on ELF is because the gold linker has issues with it. Luckily gold has been deprecated with GCC 15 2 and seems to be unable to bootstrap rustc anyway 3. As such we shouldn't really care about supporting gold.This would also allow re-enabling start-stop-gc with lld.
cc #93798
Likely fixes #85045
Footnotes
https://llvm.org/docs/LangRef.html#the-llvm-compiler-used-global-variable ↩
https://lists.gnu.org/archive/html/info-gnu/2025-02/msg00001.html ↩
https://github.com/rust-lang/rust/issues/139425 ↩