Re: [Xen-devel] Xen-unstable staging build broken by pvshim patches.

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 13/08/2019 22:03, Sander Eikelenboom wrote:
> On 13/08/2019 15:31, Andrew Cooper wrote:
>> On 13/08/2019 12:51, Sander Eikelenboom wrote:
>>> On 13/08/2019 13:21, Andrew Cooper wrote:
>>>> On 09/08/2019 00:28, Sander Eikelenboom wrote:
>>>>> On 09/08/2019 00:44, Andrew Cooper wrote:
>>>>>> On 08/08/2019 23:34, Sander Eikelenboom wrote:
>>>>>>> On 08/08/2019 23:14, Andrew Cooper wrote:
>>>>>>>> On 08/08/2019 22:16, Sander Eikelenboom wrote:
>>>>>>>>> On 08/08/2019 23:05, Andrew Cooper wrote:
>>>>>>>>>> On 08/08/2019 21:59, Sander Eikelenboom wrote:
>>>>>>>>>>> Hi Andrew,
>>>>>>>>>>>
>>>>>>>>>>> It seems the pvshim patches in xen-unstable staging break the build on my machine.
>>>>>>>>>>> I cloned a fresh tree to be sure, haven't checked which of the two commits causes it:
>>>>>>>>>>> 060f4eee0fb408b316548775ab921e16b7acd0e0 or 32b1d62887d01f85f0c1d2e0103f69f74e1f6fa3
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>> Sander
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> [ -d //usr/local/lib/xen/boot ] || /usr/src/new/xen-unstable/tools/firmware/../../tools/cross-install -d -m0755 -p //usr/local/lib/xen/boot
>>>>>>>>>>> [ -d //usr/local/lib/debug/usr/local/lib/xen/boot ] || /usr/src/new/xen-unstable/tools/firmware/../../tools/cross-install -d -m0755 -p //usr/local/lib/debug/usr/local/lib/xen/boot
>>>>>>>>>>> [ ! -e hvmloader/hvmloader ] || /usr/src/new/xen-unstable/tools/firmware/../../tools/cross-install -m0644 -p hvmloader/hvmloader //usr/local/lib/xen/boot
>>>>>>>>>>> /usr/src/new/xen-unstable/tools/firmware/../../tools/cross-install -m0644 -p seabios-dir/out/bios.bin //usr/local/lib/xen/boot/seabios.bin
>>>>>>>>>>> /usr/src/new/xen-unstable/tools/firmware/../../tools/cross-install -m0644 -p xen-dir/xen-shim //usr/local/lib/xen/boot/xen-shim
>>>>>>>>>>> install: cannot stat 'xen-dir/xen-shim': No such file or directory
>>>>>>>>>>> make[4]: *** [Makefile:52: install] Error 1
>>>>>>>>>>> make[4]: Leaving directory '/usr/src/new/xen-unstable/tools/firmware'
>>>>>>>>>>> make[3]: *** [/usr/src/new/xen-unstable/tools/../tools/Rules.mk:237: subdir-install-firmware] Error 2
>>>>>>>>>>> make[3]: Leaving directory '/usr/src/new/xen-unstable/tools'
>>>>>>>>>>> make[2]: *** [/usr/src/new/xen-unstable/tools/../tools/Rules.mk:232: subdirs-install] Error 2
>>>>>>>>>>> make[2]: Leaving directory '/usr/src/new/xen-unstable/tools'
>>>>>>>>>>> make[1]: *** [Makefile:73: install] Error 2
>>>>>>>>>>> make[1]: Leaving directory '/usr/src/new/xen-unstable/tools'
>>>>>>>>>>> make: *** [Makefile:131: install-tools] Error 2
>>>>>>>>>> That's weird.
>>>>>>>>>>
>>>>>>>>>> Do you have the full log?  The real failure was somewhere earlier where
>>>>>>>>>> xen-shim didn't get started.
>>>>>>>>>>
>>>>>>>>>> ~Andrew
>>>>>>>>>>
>>>>>>>>> Hmm if forgot and thus forgot to mention my build script disables some stuff:
>>>>>>>>> ./configure --disable-qemu-traditional --disable-stubdom --disable-docs --disable-rombios
>>>>>>>>>
>>>>>>>>> Could be that one of those doesn't work anymore.
>>>>>>>> The only interesting one would be --disable-rombios, which does make
>>>>>>>> changes in this area of the build, but everything I changed was inside
>>>>>>>> the xen-dir/ directory so shouldn't interact.>
>>>>>>>> ~Andrew
>>>>>>>>
>>>>>>> It indeed seems to be some interaction with --disable-rombios, with just
>>>>>>> a plain ./configure it builds fine.
>>>>>>> Logs when building with --disable-rombios are attached.
>>>>>> Right.  So the build itself works, but the subsequent `make install` fails.
>>>>>>
>>>>>> And to confirm, a build of 8d54a6adf (the parent of my first shim
>>>>>> commit) works entirely fine?
>>>>>>
>>>>>> ~Andrew
>>>>>>
>>>>> Just rechecked, and yes that builds and installs fine (with --disable-rombios).
>>>> Which base distro are you using?  I'm unable to reproduce any build
>>>> failures locally.
>>>>
>>>> ~Andrew
>>>>
>>> Debian 10 / Buster.
>> Do you have your full build script available, and is it built fully from
>> clean?
>>
>> How beefy is your build machine?  From the logs it is clearly a parallel
>> build but I don't see an explicit -j in the logs.
>>
>> I still cant reproduce this, even in a buster container.
>>
>> ~Andrew
>>
> The machine is not that beefy, but a six core AMD, but no OOMs or anything.
>
> The script is basically just and some changing of dirs:
> make clean && ./configure --disable-qemu-traditional --disable-stubdom --disable-docs --disable-rombios && make -j6 && make -j6 install
>
> I tried some variants just plain from the command line without any scripts:
> After a fresh clone of current xen-unstable staging branch.
>
> Fails:    make clean && ./configure --disable-rombios && make -j6 && make -j6 install
> Fails:    make clean && ./configure --disable-rombios && make -j4 && make -j4 install
> Fails:    make clean && ./configure --disable-rombios && make -j2 && make -j2 install
> Succeeds: make clean && ./configure --disable-rombios && make && make install
>
> Succeeds: make clean && ./configure && make -j2 && make -j2 install

What about j4 and j6 of these?

>
> So to recap:
>     Some how on my systeem (Debian buster) with my build tools a parallel build with --disable-rombios fails.
>     A non parallel build with --disable-rombios succeeds.
>     And reverting the "pv shim" patches makes it build again in parallel with --disable-rombios.
>
> And last but not least it seems to work on your systems with your build tools. 
>
> So I would end up with either:
>    - a difference in build tools ?
>    - and/or some unexpected dependency in the code that can go wrong timing wise in a parallel build ?

It must be something timing dependent, or I would expect to have
reproduced it with your instructions so far.  (Frankly, by this point,
I'd also expect someone else to have stumbled over it as well.)

It is almost certainly something which isn't quite parallel-safe in
tools/firmware, but I'm beginning to suspect that rombios is a bit of a
red herring and all it is doing is skewing the timing enough to cause
the opposite behaviour.

~Andrew

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