Re: Building Xen 4.14 on Debian Bullseye (WAS Re: Xen compile error)

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi,

> On 12 Oct 2020, at 10:57, Bertrand Marquis <bertrand.marquis@xxxxxxx> wrote:
> 
> Hi,
> 
>> On 9 Oct 2020, at 22:14, Hans van Kranenburg <hans@xxxxxxxxxxx> wrote:
>> 
>> On 10/9/20 7:40 PM, Julien Grall wrote:
>>> Hi,
>>> 
>>> Thank you for the report.
>>> 
>>> On 08/10/2020 13:28, ba1020@xxxxxxxxxxxxx wrote:
>>>> i try to compile the lates Release 4.14.0 and get stuck here
>>>> 
>>> In general, I would suggest to use the branch stable-4.14 or 
>>> staging-4.14 as we may have fixed some bugs which unfortunately slipped 
>>> in the release.
>>> 
>>> However, for your situation, this would have unfortunately not helped 
>>> because the commit d25cc3ec93eb "libxl: workaround gcc 10.2 
>>> maybe-uninitialized warning" is not present.
>>> 
>>> I know that Debian is looking to get Xen 4.14 build with the GCC 10. I 
>>> have CCed Ian and Hans who may be able to assist you if you encounter 
>>> more bug.
>> 
>> For Debian, we need to get it to build on a couple of archs. We're
>> currently trying to get over this hurdle.
>> 
>> https://buildd.debian.org/status/package.php?p=xen&suite=experimental
>> 
>> You need at least these:
>> 
>> * d25cc3ec93eb ("libxl: workaround gcc 10.2 maybe-uninitialized warning")
>> * fff1b7f50e75 ("libxl: fix -Werror=stringop-truncation in
>> libxl__prepare_sockaddr_un")
>> * 5d45ecabe3c0 ("xen/arm64: force gcc 10+ to always inline generic
>> atomics helpers")
>> 
>> There's also a failure in tools/xenpmd [armhf], which is caused by a
>> compiler bug, we chose to unblock it by putting in a temporary
>> workaround for now, waiting for what upstream will do about it (or while
>> waiting for fix in gcc):
>> 
>> https://salsa.debian.org/xen-team/debian-xen/-/commit/bb84bb24b55b7906c8dadd736ae1ee0ac22b1e12
>> -> "tools/xenpmd: work around gcc 10 bug for xenpmd.c", commit id might
>> be lost because of heavy rebasing.
> 
> I also came into this one on friday.
> 
> I will push a patch today or tomorrow to fix it on xen-devel and we should 
> backport it after. 

I pushed a patch on the mailing list for this one:
https://lists.xenproject.org/archives/html/xen-devel/2020-10/msg00899.html

Bertrand

> 
>> 
>>> In regard to upstream, I think we want to get 4.14 building out-of-box 
>>> with GCC 10 so distros can easily adopt it.
>> 
>> The three ones mentioned above are definitely backport candidates for
>> 4.14 already.
> 
> We need to backport those to 4.14 definitely.
> Yocto is also using gcc10 so i can also use it to test those.
> 
> Regards
> Bertrand 
> 
>> 
>>> I will send an e-mail to request a backport for the commit d25cc3ec93eb 
>>> "libxl: workaround gcc 10.2 maybe-uninitialized warning".
>>> 
>>> Best regards,
>>> 
>>>> 
>>>> 
>>>> libxlu_pci.c: In function ‘xlu_pci_parse_bdf’:
>>>> libxlu_pci.c:32:18: error: ‘func’ may be used uninitialized in this 
>>>> function [-Werror=maybe-uninitialized]
>>>>   32 |     pcidev->func = func;
>>>>      |     ~~~~~~~~~~~~~^~~~~~
>>>> libxlu_pci.c:51:29: note: ‘func’ was declared here
>>>>   51 |     unsigned dom, bus, dev, func, vslot = 0;
>>>>      |                             ^~~~
>>>> libxlu_pci.c:31:17: error: ‘dev’ may be used uninitialized in this 
>>>> function [-Werror=maybe-uninitialized]
>>>>   31 |     pcidev->dev = dev;
>>>>      |     ~~~~~~~~~~~~^~~~~
>>>> libxlu_pci.c:51:24: note: ‘dev’ was declared here
>>>>   51 |     unsigned dom, bus, dev, func, vslot = 0;
>>>>      |                        ^~~
>>>> libxlu_pci.c:30:17: error: ‘bus’ may be used uninitialized in this 
>>>> function [-Werror=maybe-uninitialized]
>>>>   30 |     pcidev->bus = bus;
>>>>      |     ~~~~~~~~~~~~^~~~~
>>>> libxlu_pci.c:51:19: note: ‘bus’ was declared here
>>>>   51 |     unsigned dom, bus, dev, func, vslot = 0;
>>>>      |                   ^~~
>>>> libxlu_pci.c:29:20: error: ‘dom’ may be used uninitialized in this 
>>>> function [-Werror=maybe-uninitialized]
>>>>   29 |     pcidev->domain = domain;
>>>>      |     ~~~~~~~~~~~~~~~^~~~~~~~
>>>> libxlu_pci.c:51:14: note: ‘dom’ was declared here
>>>>   51 |     unsigned dom, bus, dev, func, vslot = 0;
>>>>      |              ^~~
>>>> cc1: all warnings being treated as errors
>>>> make[5]: *** [/home/adminjs/xen/tools/libxl/../../tools/Rules.mk:216: 
>>>> libxlu_pci.o] Error 1
>>>> make[5]: *** Waiting for unfinished jobs....
>>>> make[5]: Leaving directory '/home/adminjs/xen/tools/libxl'
>>>> make[4]: *** [/home/adminjs/xen/tools/../tools/Rules.mk:240: 
>>>> subdir-install-libxl] Error 2
>>>> make[4]: Leaving directory '/home/adminjs/xen/tools'
>>>> make[3]: *** [/home/adminjs/xen/tools/../tools/Rules.mk:235: 
>>>> subdirs-install] Error 2
>>>> make[3]: Leaving directory '/home/adminjs/xen/tools'
>>>> make[2]: *** [Makefile:72: install] Error 2
>>>> make[2]: Leaving directory '/home/adminjs/xen/tools'
>>>> make[1]: *** [Makefile:134: install-tools] Error 2
>>>> make[1]: Leaving directory '/home/adminjs/xen'
>>>> make: *** [Makefile:170: world] Error 2
>> 
>> Have fun,
>> Hans