Re: [Qemu-devel] [RFC PATCH 0/5] Add configure flag to disable TCG

[Alexander Graf]

On 03.09.2011, at 13:58, Blue Swirl wrote:

> On Fri, Sep 2, 2011 at 9:47 PM, Anthony Liguori <address@hidden> wrote:
>> Hi,
>> 
>> There have been a few attempts in the past to allow TCG to be disabled
>> at build time.  Recently, Alex made the suggestion that we could do it by 
>> using
>> the same trick that we used to introduce kvm support.  That involves 
>> introducing
>> a tcg_enabled() macro that will be (0) if TCG is disabled in the build.
>> 
>> GCC is smart enough to do dead code elimination if it sees an if (0) and the
>> result is that if you can do:
> 
> Is this also true for gcc optimization -O0? Didn't we have breakages
> because of similar issues recently?

We obviously need to provide stubs for code that doesn't get compiled with 
--disable-tcg, but we do the same for KVM and Xen today. I agree though that we 
should have a buildbot running a build with -O0 (--enable-debug) to make sure 
nothing slips through.


Alex