Re: [Qemu-devel] [PATCH v2] test: port postcopy test to ppc64

[Laurent Vivier <lvivier@redhat.com>]

On 26/07/2016 11:28, Thomas Huth wrote:
> On 26.07.2016 11:23, Laurent Vivier wrote:
>>
>>
>> On 23/07/2016 08:30, David Gibson wrote:
>>> On Fri, Jul 22, 2016 at 09:28:58AM +0200, Laurent Vivier wrote:
>>>>
>>>>
>>>> On 22/07/2016 08:43, David Gibson wrote:
>>>>> On Thu, Jul 21, 2016 at 06:47:56PM +0200, Laurent Vivier wrote:
>>>>>> As userfaultfd syscall is available on powerpc, migration
>>>>>> postcopy can be used.
>>>>>>
>>>>>> This patch adds the support needed to test this on powerpc,
>>>>>> instead of using a bootsector to run code to modify memory,
>>>>>> we use a FORTH script in "boot-command" property.
>>>>>>
>>>>>> As spapr machine doesn't support "-prom-env" argument
>>>>>> (the nvram is initialized by SLOF and not by QEMU),
>>>>>> "boot-command" is provided to SLOF via a file mapped nvram
>>>>>> (with "-drive file=...,if=pflash")
>>>>>>
>>>>>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>>>>>> ---
>>>>>> v2: move FORTH script directly in sprintf()
>>>>>>     use openbios_firmware_abi.h
>>>>>>     remove useless "default" case
>>>>>>
>>>>>>  tests/Makefile.include |   1 +
>>>>>>  tests/postcopy-test.c  | 116 +++++++++++++++++++++++++++++++++++++++++--------
>>>>>>  2 files changed, 98 insertions(+), 19 deletions(-)
>>>>>
>>>>> There's a mostly cosmetic problem with this.  If you run make check
>>>>> for a ppc64 target on an x86 machine, you get:
>>>>>
>>>>> GTESTER check-qtest-ppc64
>>>>> "kvm" accelerator not found.
>>>>> "kvm" accelerator not found.
>>>>
>>>> I think this is because of "-machine accel=kvm:tcg", it tries to use kvm
>>>> and fall back to tcg.
>>>>
>>>> accel.c:
>>>>
>>>>      80 void configure_accelerator(MachineState *ms)
>>>>      81 {
>>>> ...
>>>>     100         acc = accel_find(buf);
>>>>     101         if (!acc) {
>>>>     102             fprintf(stderr, "\"%s\" accelerator not found.\n", buf);
>>>>     103             continue;
>>>>     104         }
>>>>
>>>> We can remove the "-machine" argument to use the default instead (tcg or
>>>> kvm).
>>>
>>> That sounds like a good option for a general test.
>>
>> In fact, we can't: we need to add a "-machine accel=XXXX" to our command
>> line to override the "-machine accel=qtest" provided by the qtest
>> framework. If we don't override it, the machine doesn't start.
> 
> Would it work if you'd added some magic with "#ifdef CONFIG_KVM" here?

I think it needs to be dynamic as the same binary test is used on x86 to
test x86 and ppc64, and vice-versa. I'm going to check if we have
something like "qtest_get_accel()"...

Thanks,
Laurent