[vfio-users] 'dnf update' killed working VM

[Laszlo Ersek]

On 08/11/17 02:39, Laszlo Ersek wrote:
> 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>

Thank you Alex for the bisection and for testing the v1 patch.

The v2 patch has been pushed to the edk2 repo:

https://bugzilla.tianocore.org/show_bug.cgi?id=657#c10

Thanks
Laszlo