Re: [Qemu-devel] [PATCH] target-i386: Enable "check" mode by default

[Paolo Bonzini <pbonzini@redhat.com>]

On 26/08/2015 18:50, Eduardo Habkost wrote:
> Current default behavior of QEMU is to silently disable features that
> are not supported by the host when a CPU model is requested in the
> command-line. This means that in addition to risking breaking guest ABI
> by default, we are silent about it.
> 
> I would like to enable "enforce" by default, but this can easily break
> existing production systems because of the way libvirt makes assumptions
> about CPU models today (this will change in the future, once QEMU
> provide a proper interface for checking if a CPU model is runnable).
> 
> But there's no reason we should be silent about it. So, change
> target-i386 to enable "check" mode by default so at least we have some
> warning printed to stderr (and hopefully logged somewhere) when QEMU
> disables a feature that is not supported by the host system.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  target-i386/cpu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

This adds a warning to TCG with the default qemu32/qemu64 CPU models,
due to lack of DE implementation in TCG.  It can be fixed before
release, so this patch is okay.  But please remind me to do it, or
implement it yourself. :)

Paolo