Re: [PATCH 0/3] configure: Do not build TCG or link with capstone if not necessary

[Paolo Bonzini]

On 20/01/21 16:19, Philippe Mathieu-Daudé wrote:
> We do not need TCG and capstone all the times. In some
> configuration we can leave them out.
>
> Last patch emit a warning when a user explicitly select an
> accelerator that the build with not use.
>
> Philippe Mathieu-Daudé (3):
>    configure: Do not build TCG if not necessary
>    configure: Do not build/check for capstone when emulation is disabled
>    configure: Emit warning when accelerator requested but not needed
>
>   configure | 37 ++++++++++++++++++++++++++++++++++++-
>   1 file changed, 36 insertions(+), 1 deletion(-)

Nice, but I have some remarks on how the patches are done. :)

For patch 1, which files are not compiled with the patch that were 
compiled without?

For patch 2, I think it's enough to add "build_by_default: false" to 
libcapstone (and while you're at it, to libslirp and libfdt).

Finally, I would prefer patch 3 to be done in Meson, right before the 
summary() call.  You can use config_all to check, like

if get_option('kvm').enabled() and not config_all.has_key('CONFIG_KVM')

etc.  This will also warn for e.g. --enable-kvm 
--target-list=sh4-softmmu, which could be considered an improvement over 
your patch.

Paolo