[PATCH] Revert "qemux86-64: Reduce tuning to core2-64"

[PATCH] Revert "qemux86-64: Reduce tuning to core2-64"

[Richard Purdie]

This was originally applied as our autobuilder had older hardware and couldn't
cope with the newer settings. This has been resolved in the new cluster so we
can go back to the newer tuning, which software is now more likely to need.

This reverts commit 369b1dfa28b1791d45f068acc765190defecd460.
---
 meta/conf/machine/include/x86/qemuboot-x86.inc | 4 ++--
 meta/conf/machine/qemux86-64.conf              | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/meta/conf/machine/include/x86/qemuboot-x86.inc b/meta/conf/machine/include/x86/qemuboot-x86.inc
index 6ae03633aea..82ef4a0b732 100644
--- a/meta/conf/machine/include/x86/qemuboot-x86.inc
+++ b/meta/conf/machine/include/x86/qemuboot-x86.inc
@@ -4,8 +4,8 @@ QB_SMP ?= "-smp 4"
 QB_CPU:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
 QB_CPU_KVM:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
 
-QB_CPU:x86-64 ?= "-cpu IvyBridge -machine q35,i8042=off"
-QB_CPU_KVM:x86-64 ?= "-cpu IvyBridge -machine q35,i8042=off"
+QB_CPU:x86-64 ?= "-cpu Skylake-Client -machine q35,i8042=off"
+QB_CPU_KVM:x86-64 ?= "-cpu Skylake-Client -machine q35,i8042=off"
 
 QB_AUDIO_DRV = "alsa"
 QB_AUDIO_OPT = "-device AC97"
diff --git a/meta/conf/machine/qemux86-64.conf b/meta/conf/machine/qemux86-64.conf
index 62108b703b6..8aac7634b75 100644
--- a/meta/conf/machine/qemux86-64.conf
+++ b/meta/conf/machine/qemux86-64.conf
@@ -3,7 +3,7 @@
 #@DESCRIPTION: Machine configuration for running an x86-64 system on QEMU
 
 require conf/machine/include/qemu.inc
-DEFAULTTUNE ?= "core2-64"
+DEFAULTTUNE ?= "x86-64-v3"
 require conf/machine/include/x86/tune-x86-64-v3.inc
 require conf/machine/include/x86/qemuboot-x86.inc
 

Re: [OE-core] [PATCH] Revert "qemux86-64: Reduce tuning to core2-64"

[Khem Raj]

On Sun, Aug 10, 2025 at 3:25 PM Richard Purdie via
lists.openembedded.org
<richard.purdie=linuxfoundation.org@lists.openembedded.org> wrote:
>
> This was originally applied as our autobuilder had older hardware and couldn't
> cope with the newer settings. This has been resolved in the new cluster so we
> can go back to the newer tuning, which software is now more likely to need.
>
> This reverts commit 369b1dfa28b1791d45f068acc765190defecd460.

LGTM
solves - https://github.com/openembedded/meta-openembedded/pull/984

> ---
>  meta/conf/machine/include/x86/qemuboot-x86.inc | 4 ++--
>  meta/conf/machine/qemux86-64.conf              | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/meta/conf/machine/include/x86/qemuboot-x86.inc b/meta/conf/machine/include/x86/qemuboot-x86.inc
> index 6ae03633aea..82ef4a0b732 100644
> --- a/meta/conf/machine/include/x86/qemuboot-x86.inc
> +++ b/meta/conf/machine/include/x86/qemuboot-x86.inc
> @@ -4,8 +4,8 @@ QB_SMP ?= "-smp 4"
>  QB_CPU:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
>  QB_CPU_KVM:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
>
> -QB_CPU:x86-64 ?= "-cpu IvyBridge -machine q35,i8042=off"
> -QB_CPU_KVM:x86-64 ?= "-cpu IvyBridge -machine q35,i8042=off"
> +QB_CPU:x86-64 ?= "-cpu Skylake-Client -machine q35,i8042=off"
> +QB_CPU_KVM:x86-64 ?= "-cpu Skylake-Client -machine q35,i8042=off"
>
>  QB_AUDIO_DRV = "alsa"
>  QB_AUDIO_OPT = "-device AC97"
> diff --git a/meta/conf/machine/qemux86-64.conf b/meta/conf/machine/qemux86-64.conf
> index 62108b703b6..8aac7634b75 100644
> --- a/meta/conf/machine/qemux86-64.conf
> +++ b/meta/conf/machine/qemux86-64.conf
> @@ -3,7 +3,7 @@
>  #@DESCRIPTION: Machine configuration for running an x86-64 system on QEMU
>
>  require conf/machine/include/qemu.inc
> -DEFAULTTUNE ?= "core2-64"
> +DEFAULTTUNE ?= "x86-64-v3"
>  require conf/machine/include/x86/tune-x86-64-v3.inc
>  require conf/machine/include/x86/qemuboot-x86.inc
>
>
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Re: [OE-core] [PATCH] Revert "qemux86-64: Reduce tuning to core2-64"

[Alexander Kanavin]

On Mon, 11 Aug 2025 at 00:25, Richard Purdie via
lists.openembedded.org
<richard.purdie=linuxfoundation.org@lists.openembedded.org> wrote:
>
> This was originally applied as our autobuilder had older hardware and couldn't
> cope with the newer settings. This has been resolved in the new cluster so we
> can go back to the newer tuning, which software is now more likely to need.

The other reason was that qemu's TCG implementation of these v3
instructions back then was very new and had subtle bugs which have
since been fixed.

This change merits a mention in release notes:

======
qemux86-64 MACHINE now defaults to x86-64-v3 micro-architecture level

The previous default was Core 2 era processors. This change means that
the toolchain is configured to build for that level, and qemu is
configured to emulate it.

v3 level adds support for AVX/AVX2/BMI/BMI2/F16C and other newer
instructions which are seeing increasing usage in modern software and
add performance benefits. Please see
https://en.wikipedia.org/wiki/X86-64#Microarchitecture_levels for
definition of the levels and lists of Intel/AMD CPUs where support for
the instructions was first added.

Note that if qemu system emulation is used on an x86 build machine
with kvm enabled, then the build machine's CPU must also be recent
enough to support these instructions natively.
======

Alex

Re: [OE-core] [PATCH] Revert "qemux86-64: Reduce tuning to core2-64"

[Alexander Kanavin]

On Mon, 11 Aug 2025 at 11:25, Alexander Kanavin <alex.kanavin@gmail.com> wrote:
>
> On Mon, 11 Aug 2025 at 00:25, Richard Purdie via
> lists.openembedded.org
> <richard.purdie=linuxfoundation.org@lists.openembedded.org> wrote:
> >
> > This was originally applied as our autobuilder had older hardware and couldn't
> > cope with the newer settings. This has been resolved in the new cluster so we
> > can go back to the newer tuning, which software is now more likely to need.
>
> The other reason was that qemu's TCG implementation of these v3
> instructions back then was very new and had subtle bugs which have
> since been fixed.
>
> This change merits a mention in release notes:
>
> ======
> qemux86-64 MACHINE now defaults to x86-64-v3 micro-architecture level
>
> The previous default was Core 2 era processors. This change means that
> the toolchain is configured to build for that level, and qemu is
> configured to emulate it.
>
> v3 level adds support for AVX/AVX2/BMI/BMI2/F16C and other newer
> instructions which are seeing increasing usage in modern software and
> add performance benefits. Please see
> https://en.wikipedia.org/wiki/X86-64#Microarchitecture_levels for
> definition of the levels and lists of Intel/AMD CPUs where support for
> the instructions was first added.
>
> Note that if qemu system emulation is used on an x86 build machine
> with kvm enabled, then the build machine's CPU must also be recent
> enough to support these instructions natively.
> ======


The change has now merged, so the above can be added to the docs too.

Alex

Re: [OE-core] [PATCH] Revert "qemux86-64: Reduce tuning to core2-64"

[Mathieu Dubois-Briand]

On Mon Aug 11, 2025 at 12:25 AM CEST, Richard Purdie via lists.openembedded.org wrote:
> This was originally applied as our autobuilder had older hardware and couldn't
> cope with the newer settings. This has been resolved in the new cluster so we
> can go back to the newer tuning, which software is now more likely to need.
>
> This reverts commit 369b1dfa28b1791d45f068acc765190defecd460.
> ---

Hi Richard,

I believe this is breaking numpy ptests. I'm not sure to understand why,
but git bisect points on this change and it is confirmed by only failing
on x86-64.

Failed ptests:
{'python3-numpy': ['python3.13/site-packages/numpy/_core/tests/test_umath_accuracy.py:TestAccuracy.test_validate_transcendentals']}

https://autobuilder.yoctoproject.org/valkyrie/#/builders/73/builds/2067
https://valkyrie.yocto.io/pub/non-release/20250811-33/testresults/qemux86-64-ptest/core-image-ptest-python3-numpy/

Best regards,
Mathieu

-- 
Mathieu Dubois-Briand, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [OE-core] [PATCH] Revert "qemux86-64: Reduce tuning to core2-64"

[Khem Raj]

On Mon, Aug 11, 2025 at 5:44 AM Mathieu Dubois-Briand via
lists.openembedded.org
<mathieu.dubois-briand=bootlin.com@lists.openembedded.org> wrote:
>
> On Mon Aug 11, 2025 at 12:25 AM CEST, Richard Purdie via lists.openembedded.org wrote:
> > This was originally applied as our autobuilder had older hardware and couldn't
> > cope with the newer settings. This has been resolved in the new cluster so we
> > can go back to the newer tuning, which software is now more likely to need.
> >
> > This reverts commit 369b1dfa28b1791d45f068acc765190defecd460.
> > ---
>
> Hi Richard,
>
> I believe this is breaking numpy ptests. I'm not sure to understand why,
> but git bisect points on this change and it is confirmed by only failing
> on x86-64.
>
> Failed ptests:
> {'python3-numpy': ['python3.13/site-packages/numpy/_core/tests/test_umath_accuracy.py:TestAccuracy.test_validate_transcendentals']}
>
> https://autobuilder.yoctoproject.org/valkyrie/#/builders/73/builds/2067
> https://valkyrie.yocto.io/pub/non-release/20250811-33/testresults/qemux86-64-ptest/core-image-ptest-python3-numpy/
>

The failure is certainly due to this change, There is a known defect
upstream [1], It has not yet been resolved. We can skip this test
until
then. I am testing a patch to do so and will send out shortly

[1] https://github.com/numpy/numpy/issues/27460

> Best regards,
> Mathieu
>
> --
> Mathieu Dubois-Briand, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>
>
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Re: [OE-core] [PATCH] Revert "qemux86-64: Reduce tuning to core2-64"

[Etienne Cordonnier]

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Sorry, I had missed that
https://patchwork.yoctoproject.org/project/oe-core/patch/20250810222523.2487072-1-richard.purdie@linuxfoundation.org/
had been sent in the meanwhile. You can ignore my patch.

On Mon, Aug 11, 2025 at 10:15 AM Etienne Cordonnier via
lists.openembedded.org <ecordonnier=snap.com@lists.openembedded.org> wrote:

> From: Etienne Cordonnier <ecordonnier@snap.com>
>
> This reverts commit 3d67b6c60fa968cd36b51c63e2a7f11bb87dd315 which
> mentions "We can revisit this in a year or two
> as we should be ready then.".
>
> Reverting this commit allows perfetto to work out of the box with
> qemux86-64. At the moment perfetto prints this error on qemux86-64:
> ```
> root@qemux86-64:~# tracebox --txt -c /tmp/config.pbtxt -o
> /tmp/perfetto-trace.pb
> This executable requires a x86_64 cpu that supports SSE4.2, BMI2 and AVX2.
> Rebuild with enable_perfetto_x64_cpu_opt=false.
> ```
> ---
>  meta/conf/machine/include/x86/qemuboot-x86.inc | 4 ++--
>  meta/conf/machine/qemux86-64.conf              | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/meta/conf/machine/include/x86/qemuboot-x86.inc
> b/meta/conf/machine/include/x86/qemuboot-x86.inc
> index 6ae03633aea..82ef4a0b732 100644
> --- a/meta/conf/machine/include/x86/qemuboot-x86.inc
> +++ b/meta/conf/machine/include/x86/qemuboot-x86.inc
> @@ -4,8 +4,8 @@ QB_SMP ?= "-smp 4"
>  QB_CPU:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
>  QB_CPU_KVM:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
>
> -QB_CPU:x86-64 ?= "-cpu IvyBridge -machine q35,i8042=off"
> -QB_CPU_KVM:x86-64 ?= "-cpu IvyBridge -machine q35,i8042=off"
> +QB_CPU:x86-64 ?= "-cpu Skylake-Client -machine q35,i8042=off"
> +QB_CPU_KVM:x86-64 ?= "-cpu Skylake-Client -machine q35,i8042=off"
>
>  QB_AUDIO_DRV = "alsa"
>  QB_AUDIO_OPT = "-device AC97"
> diff --git a/meta/conf/machine/qemux86-64.conf
> b/meta/conf/machine/qemux86-64.conf
> index 62108b703b6..8aac7634b75 100644
> --- a/meta/conf/machine/qemux86-64.conf
> +++ b/meta/conf/machine/qemux86-64.conf
> @@ -3,7 +3,7 @@
>  #@DESCRIPTION: Machine configuration for running an x86-64 system on QEMU
>
>  require conf/machine/include/qemu.inc
> -DEFAULTTUNE ?= "core2-64"
> +DEFAULTTUNE ?= "x86-64-v3"
>  require conf/machine/include/x86/tune-x86-64-v3.inc
>  require conf/machine/include/x86/qemuboot-x86.inc
>
> --
> 2.43.0
>
>
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