[OE-core] [PATCH] tune-core2: use n270 instead of core2duo

[Andre McCurdy]

On Thu, Sep 13, 2018 at 4:46 PM, Anuj Mittal <anuj.mittal at intel.com> wrote:
> On 09/14/2018 06:50 AM, Andre McCurdy wrote:
>> On Thu, Sep 13, 2018 at 3:16 PM, Martin Jansa <martin.jansa at gmail.com> wrote:
>>> Is this different issue than what was discussed in:
>>> https://www.mail-archive.com/openembedded-core@lists.openembedded.org/msg109516.html
>>>
>>> The message is slightly different (might be changed in newer qemu used now),
>>> but the issue I had before was that features of selected -cpu and host cpu
>>> didn't match and qemu failed with:
>>> qemu-system-x86_64: warning: host doesn't support requested feature:
>>> CPUID.01H:EDX.ss [bit 27]
>>> when some features were missing and kvm was used.
>>>
>
> The message is different in this case because that one was for KVM, this
> one is when using user space emulation so it's checking what can be
> emulated and what is being asked by way of -cpu parameter [1].
>
>>> If it's the same root cause, then it's not a bug in qemu.
>>
>> Thanks. Looks like it could be the same issue - if qemu is running
>> with KVM on a host which isn't natively compatible with the full
>> core2duo feature set.
>
> Similar problem, but a different issue in my opinion. So these features
> (lm, syscall) that we see warnings about are only seen when building for
> 32 bit while running qemu-i386 for executing postinsts.
>
> Looking at qemu commit logs, it doesn't look like these two features are
> supported with qemu-i386. So, I changed the qemu -cpu value that is used
> with qemu-i386 to a lower denominator which still supports the
> instruction set that we build for for 32 bit.

If KVM isn't involved then it does look like a qemu bug, ie the -cpu
core2duo option enables features which the emulator doesn't support.

Right?

> [1] https://wiki.qemu.org/Documentation/TCG
> [2]
> https://github.com/qemu/qemu/commit/4586f157757acc5c8edcc954289c7aa51661235c
>
>>
>> From the Yocto bug these warnings are coming from the nightly builds:
>>
>>   https://bugzilla.yoctoproject.org/show_bug.cgi?id=12916
>>
>> Has something changed recently? Have the nightly builds moved onto an
>> AMD machine?
>>
>>
>>> On Thu, Sep 13, 2018 at 11:33 PM Andre McCurdy <armccurdy at gmail.com> wrote:
>>>>
>>>> On Thu, Sep 13, 2018 at 12:25 AM, Anuj Mittal <anuj.mittal at intel.com>
>>>> wrote:
>>>>> Fixes warnings in builds using core2-32 tune:
>>>>>
>>>>> warning: TCG doesn't support requested feature:
>>>>> CPUID.80000001H:EDX.syscall [bit 11]
>>>>> warning: TCG doesn't support requested feature: CPUID.80000001H:EDX.lm
>>>>> [bit 29]
>>>>>
>>>>> when executing postinsts using qemu-i386.
>>>>>
>>>>> i386 target doesn't enable CPUID_EXT2_SYSCALL and CPUID_EXT2_LM [1]
>>>>> while cpu choice of core2duo that we use for core2-32 TUNE does [2].
>>>>> Use n270 cpu instead to use with qemu which supports SSSE3 and doesn't
>>>>> have these bits enabled [3].
>>>>>
>>>>> [1] https://github.com/qemu/qemu/blob/master/target/i386/cpu.c#L739
>>>>> [2] https://github.com/qemu/qemu/blob/master/target/i386/cpu.c#L1439
>>>>> [3] https://github.com/qemu/qemu/blob/master/target/i386/cpu.c#L1603
>>>>>
>>>>> Fixes [YOCTO #12916]
>>>>
>>>> Is this working around a bug in qemu?
>>>>
>>>>> Signed-off-by: Anuj Mittal <anuj.mittal at intel.com>> ---
>>>>>  meta/conf/machine/include/tune-core2.inc | 2 +-
>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/meta/conf/machine/include/tune-core2.inc
>>>>> b/meta/conf/machine/include/tune-core2.inc
>>>>> index c686bb4682..ddde719bde 100644
>>>>> --- a/meta/conf/machine/include/tune-core2.inc
>>>>> +++ b/meta/conf/machine/include/tune-core2.inc
>>>>> @@ -21,7 +21,7 @@ TUNE_FEATURES_tune-core2-32 =
>>>>> "${TUNE_FEATURES_tune-x86} core2"
>>>>>  BASE_LIB_tune-core2-32 = "lib"
>>>>>  TUNE_PKGARCH_tune-core2-32 = "core2-32"
>>>>>  PACKAGE_EXTRA_ARCHS_tune-core2-32 = "${PACKAGE_EXTRA_ARCHS_tune-i686}
>>>>> core2-32"
>>>>> -QEMU_EXTRAOPTIONS_core2-32 = " -cpu core2duo"
>>>>> +QEMU_EXTRAOPTIONS_core2-32 = " -cpu n270"
>>>>>
>>>>>  AVAILTUNES += "core2-64"
>>>>>  TUNE_FEATURES_tune-core2-64 = "${TUNE_FEATURES_tune-x86-64} core2"
>>>>> --
>>>>> 2.17.1
>>>>>
>>>>> --
>>>>> _______________________________________________
>>>>> Openembedded-core mailing list
>>>>> Openembedded-core at lists.openembedded.org
>>>>> http://lists.openembedded.org/mailman/listinfo/openembedded-core
>>>> --
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>