[CRIU] [PATCH 1/2] DO NOT MERGE: Move x86 VDSO code to AArch64

[Cyrill Gorcunov]

On Fri, Jul 25, 2014 at 04:16:17PM -0400, Christopher Covington wrote:
> On 07/25/2014 03:31 PM, Cyrill Gorcunov wrote:
> > On Fri, Jul 25, 2014 at 03:19:58PM -0400, Christopher Covington wrote:
> >> Purely to illustrate how exactly the AArch64 VDSO handling differs
> >> from x86 in the following patch. Not intended for merge.
> >>
> >> Signed-off-by: Christopher Covington <cov at codeaurora.org>
> > 
> > Thanks a lot! I'll think how to share a common parts (presumably
> > after the weekend).
> 
> Thanks Cyrill. Some notes on these changes:
> 
> I think this code triggers a bug in qemu-system-aarch64. It's either that or
> there's a race condition that doesn't show up on the two other simulators I've
> tried it on.

OK, good to know. I believe with time you manage to catch it.

> The vdso00 and vdso01 (with modifications) tests pass with my modified zdtm.sh.

Cool!

> 
> I didn't yet force proxification as you suggested for testing purposes.

No hurry at all.

> You brought up a point about testing changes across all architectures. I agree
> that this is currently difficult. I'm currently not testing changes on x86_64
> because my Ubuntu 12.04 workstation kernel version 3.2 is too old. My hope is
> that we can improve this.

Not only because of testing I also think we should follow kernel's style of
architecture specific code. As far as I understand kernel's vdso between
x86 and arm are handled completely separately in the kernel. That said I
think kern developers might be facing same problems as we do -- if code
is shared there is a big chance to break something while you improve code
for one architecture.

> When you made your original changes, you sent out a call for testing that I
> didn't answer because I didn't have the tests running on my system at the
> time. I'm now able to mostly run the tests and should be able to respond to
> such requests in the future.
> 
> I'm also working to document and improve how I cross compile and run the test
> suite in QEMU using a minimal root filesystem. Once this has been streamlined,
> it may be possible to integrate it into the CRIU makefiles if desired, such
> that to test for x86_64, armv6, armv7, and armv8 one could simply type:
> 
> make test_multiarch

Cool, that would be a killer feature and quite convenient to run!