Re: [PATCH 1/2] meson: Check for seccomp/cap-ng libraries if virtiofsd is enabled

[Philippe Mathieu-Daudé]

On 4/28/21 8:00 PM, Philippe Mathieu-Daudé wrote:
> On 4/28/21 6:34 PM, Richard Henderson wrote:
>> On 4/28/21 7:48 AM, Philippe Mathieu-Daudé wrote:
>>>   seccomp = not_found
>>> -if not get_option('seccomp').auto() or have_system or have_tools
>>> +if not get_option('seccomp').auto() or have_system or have_tools or
>>> not get_option('virtiofsd').auto()
>>>     seccomp = dependency('libseccomp', version: '>=2.3.0',
>>>                          required: get_option('seccomp'),
>>>                          method: 'pkg-config', kwargs: static_kwargs)
>>
>> This construct is wrong, both before and after, as I read it.
>>
>> not get_option(foo).auto() is true for both enabled and disabled.  If
>> disabled, why are we examining the dependency?  If auto, if we have all
>> of the dependencies we want to enable the feature -- if we don't probe
>> for the dependency, how can we enable it?
>>
>> This error seems to be offset by the OR have_* tests, for which the
>> logic also seems off.
>>
>> I think the test should have been
>>
>>   if (have_system or have_tools) and
> 
> Yes but virtiofsd is not a tool... It is a standalone binary.
> Maybe have_system is the culprit here:
> 
>   have_system = have_system or target.endswith('-softmmu')
> 
> We should somewhere add:
> 
>   have_system = have_system or something('virtiofsd')

So this hunk does fix the issue ...:

-- >8 --
--- a/meson.build
+++ b/meson.build
@@ -52,4 +52,5 @@
 endforeach
 have_tools = 'CONFIG_TOOLS' in config_host
+# virtiofsd depends on sysemu
+have_system = have_system or not get_option('virtiofsd').disabled()
 have_block = have_system or have_tools

---

> However I wonder if we aren't going to build many objects
> that are irrelevant for virtiofsd.

Based on top of
https://www.mail-archive.com/qemu-devel@nongnu.org/msg799069.html
to remove libsoftfloat, 216 objects are required to build virtiofsd:

[216/216] Linking target tools/virtiofsd/virtiofsd

This one-line fix seems good enough (to keep virtiofsd as a 'tool').