ppc64le and 32-bit LE userland compatibility

[Christophe Leroy]

Le 06/06/2020 à 01:54, Will Springer a écrit :
> On Saturday, May 30, 2020 3:17:24 PM PDT Will Springer wrote:
>> On Saturday, May 30, 2020 8:37:43 AM PDT Christophe Leroy wrote:
>>> There is a series at
>>> https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=173231
>>> to switch powerpc to the Generic C VDSO.
>>>
>>> Can you try and see whether it fixes your issue ?
>>>
>>> Christophe
>>
>> Sure thing, I spotted that after making the initial post. Will report
>> back with results.
>>
>> Will [she/her]
> 
> Sorry for the wait, I just sat down to work on this again yesterday.
> 
> Tested this series on top of stable/linux-5.7.y (5.7.0 at the time of
> writing), plus the one-line signal handler patch. Had to rewind to the
> state of powerpc/merge at the time of the mail before the patch would
> apply, then cherry-picked to 5.6 until I realized the patchset used some
> functionality that didn't land until 5.7, so I moved it there.
> 
> Good news is that `date` now works correctly with the vdso call in 32-bit
> LE. Bad news is it seems to have broken things on the 64-bit side—in my
> testing, Void kicks off runit but hangs after starting eudev, and in a
> Debian Stretch system, systemd doesn't get to the point of printing
> anything whatsoever. (I had to `init=/bin/sh` to confirm the date worked
> in ppcle, although in ppc64le running `date` also hung the system when it
> made the vdso call...) Not sure how to approach debugging that, so I'd
> appreciate any pointers.
> 

Does it breaks only ppc64le vdso or also ppc64 (be) vdso ?

I never had a chance to run any test on ppc64 as I only have a kernel 
cross compiler.

Would you have a chance to build and run vdsotest from 
https://github.com/nathanlynch/vdsotest ?

Thanks
Christophe