From: Yegor Yefremov via buildroot <buildroot@buildroot.org>
To: buildroot@buildroot.org
Cc: Romain Naour <romain.naour@gmail.com>
Subject: [Buildroot] [PATCH] package/qemu: host-qemu does not support AVX512 CPUs
Date: Mon, 14 Sep 2026 11:26:12 +0200 [thread overview]
Message-ID: <20260914092612.1283030-1-yegorslists@gmail.com> (raw)
From: Yegor Yefremov <yegorslists@googlemail.com>
Building gobject-introspection for an x86 CPU variant with AVX512 fails
when g-ir-scanner runs the freshly built target binaries under
qemu-user:
qemu: uncaught target signal 4 (Illegal instruction) - core dumped
The Qemu TCG engine implements AVX, AVX2, F16C, FMA3 and VAES since Qemu
7.2, but it does not implement the AVX512 instruction set at all [0].
Therefore no -cpu value passed through
BR2_PACKAGE_HOST_QEMU_USER_MODE_ARGS can make such binaries run, and
user-mode emulation is simply not possible for these CPU variants.
Mark those CPUs as unsupported by host-qemu, the same way it is already
done for x86_steamroller and x86_core_avx2. This relies on the existing
BR2_X86_CPU_HAS_AVX512 symbol, so all AVX512 capable variants are
covered, and it disables gobject-introspection and nodejs, which are the
two packages needing host-qemu in user mode.
[0] https://gitlab.com/qemu-project/qemu/-/issues/2878
Fixes:
https://autobuild.buildroot.org/results/7ed7f9c36dae1ddb965a0f0021db6cd319927b47/
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Assisted-by: Claude:claude-opus-5
---
package/qemu/Config.in.host | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/package/qemu/Config.in.host b/package/qemu/Config.in.host
index c7dd5876e5..e5379e7224 100644
--- a/package/qemu/Config.in.host
+++ b/package/qemu/Config.in.host
@@ -23,6 +23,10 @@ config BR2_PACKAGE_HOST_QEMU_ARCH_SUPPORTS
default y if BR2_xtensa
default y if BR2_x86_64
depends on !BR2_x86_steamroller && !BR2_x86_core_avx2
+ # The Qemu TCG engine does not implement the AVX512
+ # instruction set, so binaries built for such CPUs cannot be
+ # emulated.
+ depends on !BR2_X86_CPU_HAS_AVX512
depends on !BR2_powerpc_620 && !BR2_powerpc_630
config BR2_PACKAGE_HOST_QEMU_SYSTEM_ARCH_SUPPORTS
--
2.34.1
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next reply other threads:[~2026-09-14 9:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-14 9:26 Yegor Yefremov via buildroot [this message]
2026-09-16 18:57 ` [Buildroot] [PATCH] package/qemu: host-qemu does not support AVX512 CPUs Thomas Petazzoni via buildroot
2026-09-17 6:56 ` Yegor Yefremov via buildroot
2026-09-17 7:26 ` Thomas Petazzoni via buildroot
2026-09-25 14:44 ` Raphaël Mélotte via buildroot
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