Re: contrib/plugins does not build on 32-bit host

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> On 12/13/24 21:44, Pierrick Bouvier wrote:
>> Hi Richard,
>> On 12/13/24 13:47, Richard Henderson wrote:
>>> Hi,
>>>
>>> Several of the recent contrib/plugins/ patches do not build on e.g. arm32.
>>> All of the issues are related to casting between pointers and uint64_t; there is a Werror
>>> generated for casting between pointers and integers of different sizes.
>>>
>>> I suspect all of the instances will need to use separate structures to store uint64_t
>>> within the hash tables.  The hash values themselves can use uintptr_t, as "hash" by
>>> definition loses data.
>>>
>>> The following is *not* a suggested patch, just touches every place with an error to
>>> highlight all of the places.
>>>
>> This is something I already tried to fix this way, but alas, casting
>> values is not enough, we might lose information (in the case where
>> guest is 64 bits). Some plugins need a refactoring to allocate data
>> dynamically, instead of hiding it under a pointer.
>> See this previous series:
>> https://patchew.org/QEMU/20240814233645.944327-1-pierrick.bouvier@linaro.org/
>> Finally, we discussed it was not worth the effort, and Alex simply
>> deactivated plugins by default for 32 bits platform, so it should
>> not be built for arm 32 bits. If we really have someone that needs
>> this usecase, we might make the effort, but for now, it does not
>> seem worth the hassle.
>
> Hmm.  I didn't delete my 32-bit build tree, but it certainly
> re-configured.  If plugins are supposed to be disabled, something may
> be wrong there...

Something should have triggered re-running config.status and triggering
the disable. I wonder why that didn't work.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro