Re: [PATCH 03/12] tests/plugin: add test plugin for inline operations

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

On 1/11/24 19:57, Philippe Mathieu-Daudé wrote:
> Hi Pierrick,
> 
> On 11/1/24 15:23, Pierrick Bouvier wrote:
>> For now, it simply performs instruction, bb and mem count, and ensure
>> that inline vs callback versions have the same result. Later, we'll
>> extend it when new inline operations are added.
>>
>> Use existing plugins to test everything works is a bit cumbersome, as
>> different events are treated in different plugins. Thus, this new one.
>>
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>> ---
>>    tests/plugin/inline.c    | 183 +++++++++++++++++++++++++++++++++++++++
>>    tests/plugin/meson.build |   2 +-
>>    2 files changed, 184 insertions(+), 1 deletion(-)
>>    create mode 100644 tests/plugin/inline.c
> 
>> +#define MAX_CPUS 8
> 
> Where does this value come from?
> 

The plugin tests/plugin/insn.c had this constant, so I picked it up from 
here.

> Should the pluggin API provide a helper to ask TCG how many
> vCPUs are created?

In user mode, we can't know how many simultaneous threads (and thus 
vcpu) will be triggered by advance. I'm not sure if additional cpus can 
be added in system mode.

One problem though, is that when you register an inline op with a 
dynamic array, when you resize it (when detecting a new vcpu), you can't 
change it afterwards. So, you need a storage statically sized somewhere.

Your question is good, and maybe we should define a MAX constant that 
plugins should rely on, instead of a random amount.