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

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

On 13/08/2019 23:05, Andrew Cooper wrote:
> 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?

Urghh I *thought* i have seen j6 work, but the first time rechecking it didn't, 
second time it did.
j4 worked first time while rechecking.

>>
>> 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.

I think the above confirms this suspicion.

--
Sander
 
> ~Andrew
> 


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