On Mon, May 11, 2020 at 10:04:29AM -0700, Oliver Upton wrote: > On Mon, May 11, 2020 at 9:05 AM Sean Christopherson > <[email protected]> wrote: > > > > +cc a few other people that have reported this at one time or another. > > > > On Tue, May 05, 2020 at 10:12:45AM -0400, Peter Xu wrote: > > > On Mon, May 04, 2020 at 06:39:29PM -0700, Sean Christopherson wrote: > > > > On Mon, May 04, 2020 at 03:05:26PM -0400, Peter Xu wrote: > > > > > GCC 10.0.1 gives me this warning when building KVM: > > > > > > > > > > warning: ‘nr_pages_avail’ may be used uninitialized in this > > > > > function [-Wmaybe-uninitialized] > > > > > 2442 | for ( ; start_gfn <= end_gfn; start_gfn += nr_pages_avail) { > > > > > > > > > > It should not happen, but silent it. > > > > > > > > Heh, third times a charm? This has been reported and proposed twice > > > > before[1][2]. Are you using any custom compiler flags? E.g. -O3 is > > > > known > > > > to cause false positives with -Wmaybe-uninitialized. > > > > > > No, what I did was only upgrading to Fedora 32 (which will auto-upgrade > > > GCC), > > > so it should be using the default params of whatever provided. > > > > > > > > > > > If we do end up killing this warning, I'd still prefer to use > > > > uninitialized_var() over zero-initializing the variable. > > > > > > > > [1] https://lkml.kernel.org/r/[email protected] > > > > [2] https://bugzilla.kernel.org/show_bug.cgi?id=207173 > > > > > > OK, I didn't know this is a known problem and discussions going on. But I > > > guess it would be good to address this sooner because it could become a > > > common > > > warning very soon after people upgrades gcc. > > > > Ya, others are hitting this as well. It's especially painful with the > > existence of KVM_WERROR. > > > > Paolo, any preference on how to resolve this? It would appear GCC 10 got > > "smarter". > > Seems that doing absolutely nothing was the fix here :) See: > > 78a5255ffb6a ("Stop the ad-hoc games with -Wno-maybe-initialized")
Ah, perfect! Thanks Oliver.
