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From: Yegor Yefremov via buildroot <buildroot@buildroot.org>
To: buildroot@buildroot.org
Cc: Romain Naour <romain.naour@gmail.com>, thomas.petazzoni@bootlin.com
Subject: [Buildroot] [PATCH 1/3] package/qemu: drop x86_core_avx2 exclusion
Date: Thu, 17 Sep 2026 09:53:24 +0200	[thread overview]
Message-ID: <20260917075326.1256294-2-yegorslists@gmail.com> (raw)
In-Reply-To: <20260917075326.1256294-1-yegorslists@gmail.com>

From: Yegor Yefremov <yegorslists@googlemail.com>

Commit 1f7efaf89f03 ("package/qemu: do not support x86_steamroller or
x86_core_avx2") excluded BR2_x86_core_avx2 from
BR2_PACKAGE_HOST_QEMU_ARCH_SUPPORTS because binaries built for that CPU
variant crashed under qemu-user. This was done at the time of Qemu 4.2,
whose TCG engine did not implement AVX at all.

Since Qemu 7.2, the TCG engine implements AVX, AVX2, F16C, FMA3 and
VAES. In Qemu 11.0.0 (the version we currently package) and 11.1.1,
target/i386/cpu.c has:

  #define TCG_EXT_FEATURES (... | CPUID_EXT_AVX | CPUID_EXT_F16C | \
            CPUID_EXT_FMA | ...)
  #define TCG_7_0_EBX_FEATURES (... | CPUID_7_0_EBX_BMI1 | \
            CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_AVX2 | ...)

which covers everything gcc generates for -march=core-avx2.

In addition, the exclusion was inconsistent: gcc's core-avx2 is a
deprecated alias for haswell, both variants select exactly the same
BR2_X86_CPU_HAS_* symbols in arch/Config.in.x86, and haswell was never
excluded. The same goes for broadwell, skylake, zen*, x86-64-v3, ...,
which all enable AVX2 and build fine on the autobuilders.

So drop the BR2_x86_core_avx2 exclusion.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Assisted-by: Claude:claude-opus-5
---
 package/qemu/Config.in.host | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package/qemu/Config.in.host b/package/qemu/Config.in.host
index e5379e7224..48979fd7ce 100644
--- a/package/qemu/Config.in.host
+++ b/package/qemu/Config.in.host
@@ -22,7 +22,7 @@ config BR2_PACKAGE_HOST_QEMU_ARCH_SUPPORTS
 	default y if BR2_sparc64
 	default y if BR2_xtensa
 	default y if BR2_x86_64
-	depends on !BR2_x86_steamroller && !BR2_x86_core_avx2
+	depends on !BR2_x86_steamroller
 	# The Qemu TCG engine does not implement the AVX512
 	# instruction set, so binaries built for such CPUs cannot be
 	# emulated.
-- 
2.34.1

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  reply	other threads:[~2026-09-17  7:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-17  7:53 [Buildroot] [PATCH 0/3] package/qemu: fix x86 CPU variant exclusions Yegor Yefremov via buildroot
2026-09-17  7:53 ` Yegor Yefremov via buildroot [this message]
2026-09-25 14:46   ` [Buildroot] [PATCH 1/3] package/qemu: drop x86_core_avx2 exclusion Raphaël Mélotte via buildroot
2026-09-17  7:53 ` [Buildroot] [PATCH 2/3] arch/Config.in.x86: add BR2_X86_CPU_HAS_XOP Yegor Yefremov via buildroot
2026-09-25 14:46   ` Raphaël Mélotte via buildroot
2026-09-17  7:53 ` [Buildroot] [PATCH 3/3] package/qemu: host-qemu does not support XOP capable CPUs Yegor Yefremov via buildroot
2026-09-25 14:46   ` Raphaël Mélotte via buildroot
2026-09-17  9:21 ` [Buildroot] [PATCH 0/3] package/qemu: fix x86 CPU variant exclusions Thomas Petazzoni via buildroot

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