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[blacksail,51/60] rust-common: Use 64-bit time_t libc layouts for riscv32 musl

Message ID 7ef028fb9782309ad89acce0b7bccdcdd88751cc.1793867929.git.yoann.congal@smile.fr
State RFC, archived
Delegated to: Yoann Congal
Headers show
Series [blacksail,01/60] gstreamer1.0-plugins-bad: use gtk+3 dependency name | expand

Commit Message

Yoann Congal Nov. 5, 2026, 8:43 a.m. UTC 
From: Khem Raj <raj.khem@gmail.com>

musl on riscv32 only has a 64-bit time_t. The libc crate
before 0.2.190 still uses 32-bit time_t struct layouts for riscv32 musl
unless asked otherwise, so e.g. std's stat() passes a struct stat that
is about 24 bytes smaller than the 128 bytes musl writes. This corrupts
the stack, and any Rust program calling std::thread::available_parallelism()
or std::fs::metadata() crashes:

  qemu: uncaught target signal 11 (Segmentation fault) - core dumped

This affects std, which uses the vendored libc 0.2.189 in Rust 1.99.0.
Upstream fixed it in libc 0.2.190 by always using the musl 1.2 layouts
on riscv32 [1].

Until then, opt into them for riscv32 musl targets with the
libc_unstable_musl_v1_2_3 cfg, which libc 0.2.189 reads. Earlier
versions are not opted in: 0.2.174 to 0.2.188 read the
RUST_LIBC_UNSTABLE_MUSL_V1_2_3 environment variable instead, but their
riscv32 time64 layouts lack the timespec padding (up to 0.2.182) or
fail to build with duplicate __pad1/__pad2 fields (0.2.183 to 0.2.188),
and older versions have no musl time64 support.

[1] https://github.com/rust-lang/libc/pull/5508

Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit e4a1edaade3fdf413074e2006bc33097a450f827)
Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
---
 meta/classes-recipe/rust-common.bbclass | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/meta/classes-recipe/rust-common.bbclass b/meta/classes-recipe/rust-common.bbclass
index a4278af83a0..87d4d43c9bb 100644
--- a/meta/classes-recipe/rust-common.bbclass
+++ b/meta/classes-recipe/rust-common.bbclass
@@ -18,6 +18,9 @@  RUST_DEBUG_REMAP = "--remap-path-prefix=${WORKDIR}=${TARGET_DBGSRC_DIR} \
                     --remap-path-prefix=${TMPDIR}/work-shared=${TARGET_DBGSRC_DIR} \
 "
 RUSTFLAGS += "${RUSTLIB} ${RUST_DEBUG_REMAP}"
+
+# Delete it when every crate moves to use libc > 0.2.190 crate
+RUSTFLAGS:append:riscv32:libc-musl = " --cfg libc_unstable_musl_v1_2_3"
 RUSTLIB_DEP ??= "libstd-rs"
 RUST_PANIC_STRATEGY ??= "unwind"
 # See https://bugzilla.yoctoproject.org/show_bug.cgi?id=15976