[vfio-users] 'dnf update' killed working VM
Laszlo Ersek
lersek at redhat.com
Fri Aug 11 00:39:13 UTC 2017
On 08/10/17 16:54, Laszlo Ersek wrote:
> On 08/10/17 14:15, Laszlo Ersek wrote:
>
>> So I think it comes down to another toolchain difference between RHEL-7
>> and Fedora-26. Likely gcc -- the commit you identified is also related
>> to a C compiler. In particular:
>>
>> - on RHEL-7, the system compiler (gcc-4.8.5) is mapped to the "GCC48"
>> toolchain settings of edk2, which lack support for LTO (link time
>> optimization),
>>
>> - in the Fedora package's SPEC file, the "GCC49" toolchain settings are
>> selected for the build in a fixed manner, which also lack support for
>> LTO,
>>
>> - in kraxel's SPEC file, Fedora-26's gcc-7 compiler is mapped to the
>> "GCC5" toolchain settings, which *enable* LTO (for DEBUG).
>>
>> The test you suggested to David elsewhere in this thread confirms that
>> the Fedora -- well, "virt-preview" -- package, built with GCC49
>> settings, works, and that Gerd's package, built with GCC5 settings,
>> breaks.
>>
>> I'll spin up a Fedora-26 guest and build OVMF there.
>
> I confirm that building with gcc-7.1.1 on Fedora-26, using the GCC5
> toolchain settings and the DEBUG target (= optimizations enabled), the
> problem reproduces for me.
>
> Keeping everything the same except switching DEBUG to NOOPT (=
> optimizations disabled) the OVMF binary returns to working state.
>
> So, OVMF is being mis-built / mis-optimized by gcc-7.1, with the DEBUG
> GCC5 settings. I'll try to tweak both the code and the gcc flags.
Posted a patch (and CC'd you on it):
https://lists.01.org/pipermail/edk2-devel/2017-August/013125.html
Testing would be appreciated. Instructions are in the linked message.
If you reply to edk2-devel, please subscribe first (and wait for the
subscription to complete), otherwise the list will drop your email. It's
bad and I've tried to change it, but so far I've failed.
<https://bugzilla.tianocore.org/show_bug.cgi?id=451>
Thanks
Laszlo
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