Re: [PATCH v7 0/6] plugins: access values during a memory read/write

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 9/9/24 13:21, Alex Bennée wrote:
> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:
> 
>> On 9/9/24 03:00, Alex Bennée wrote:
>>> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:
>>>
>>>> On 9/5/24 08:21, Alex Bennée wrote:
>>>>> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:
>>>>>
>>>>>> This series allows plugins to know which value is read/written during a memory
>>>>>> access.
>>>>>>
>>>>>> For every memory access, we know copy this value before calling mem callbacks,
>>>>>> and those can query it using new API function:
>>>>>> - qemu_plugin_mem_get_value
>>>>> Queued to patches 1-5 to plugins/next, thanks.
>>>>> You can send the re-spun version of 6 once the review comments have
>>>>> been
>>>>> done.
>>>>>
>>>>
>>>> Thanks Alex,
>>>>
>>>> right now, my try to make check-tcg are blocked with the cross
>>>> containers who don't compile, so I'll wait for this to be resolved.
>>> Which ones?
>>
>> docker-image-debian-mips64el-cross
>> docker-image-debian-mipsel-cross
>> (about broken packages).
> 
> I have fixes for mipsel at least when I post my series.
> 
>>
>> I saw something mentioning this recently on the mailing list, so not
>> sure what would be our solution to this (ignoring?)
>>
>>>
>>>> I still wonder if having a simple aarch64/x64 test is not enough, and
>>>> covering 99.9% of the bug we could introduce in the future on this.
>>> Have you measured the code coverage of the test?
>>>
>>
>> Nope, but all the code changed is tcg-generic, so testing this on all
>> arch does not bring benefit in terms of coverage.
> 
> Would that it were so simple. Quite often which bits of the generic TCG
> code get exercised depends on the guest architecture using it. I'm not
> saying we have to go over and above to enable fiddly architectures but we
> should at least understand if the reason they fail is down to them or
> core code.

I understand your point, and will try to make this work on all arch.

> 
>> So by focusing on the "all arch" aspect, we just test tcg
>> implementation itself, instead of the plugins part.
>>
>> The problems we identified so far is compilation flags specific per
>> arch, and specific flags to emit words instruction. It does not seem
>> related to what we really want to test here.
> 
> I'm also investigating why arm-softmmu seems to be seeing more accesses
> than it should have from the test.
> 

Good!