Re: [PATCH] build-sys: error when slirp is not found and not disabled

[Daniel P . Berrangé]

On Mon, Oct 03, 2022 at 11:05:34AM +0400, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> This is an alternative configure-time solution to "[PATCH] net:
> print a more actionable error when slirp is not found".
> 
> See also "If your networking is failing after updating to the latest git
> version of QEMU..." ML thread.
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  meson.build | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/meson.build b/meson.build
> index 8dc661363f..565096001d 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -657,6 +657,12 @@ if not get_option('slirp').auto() or have_system
>    endif
>  endif
>  
> +if not get_option('slirp').disabled() and not slirp.found()
> +  error('libslirp is not explicitely disabled and was not found. ' +
> +        'Since qemu 7.2, libslirp is no longer included as a submodule ' +
> +        'fallback, you must install it on your system or 
> --disable-libslirp.')
> +endif

I understand the motivation, but this goes against the main principal
of our build time detection, which is to "do the right thing" automatically.
If libslirp is not present on the host, then I would consider the need to
pass --disable-libslirp to be a bug.

I think this pain that people see of loosing slirp support is going to be
a pretty short term problem. IMHO it suffices to print a warning message
right at the very end of configure, after everything else, just for one
or two releases.


With regards,
Daniel
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