On Wed, Mar 05, 2008 at 11:58:34AM -0800, Joe Buck wrote: > > Aurelien Jarno wrote: > > >Since version 4.3, gcc changed its behaviour concerning the x86/x86-64 > > >ABI and the direction flag, that is it now assumes that the direction > > >flag is cleared at the entry of a function and it doesn't clear once > > >more if needed. > > >... > > >I guess this has to be fixed on the kernel side, but also gcc-4.3 could > > >revert back to the old behaviour, that is clearing the direction flag > > >when entering a routine that touches it until most people are running a > > >fixed kernel. > > On Wed, Mar 05, 2008 at 08:00:42AM -0800, H. Peter Anvin wrote: > > Linux should definitely follow the ABI. This is a bug, and a pretty > > serious such. > > Unfortunately, there are a lot of kernels out there already with this > problem, and the symptoms are likely to be subtle. So even if it is true > that it is the kernel that is "in the wrong", I think we still are going > to need to give users a workaround from the gcc side as well. > > So I think gcc at least needs an *option* to revert to the old behavior, > and there's a good argument to make it the default for now, at least for > x86/x86-64 on Linux.
And for other kernels. I tested OpenBSD 4.1, FreeBSD 6.3, NetBSD 4.0, they have the same behaviour as Linux, that is they don't clear DF before calling the signal handler. I also tested Hurd, and it causes a kernel crash. -- .''`. Aurelien Jarno | GPG: 1024D/F1BCDB73 : :' : Debian developer | Electrical Engineer `. `' [EMAIL PROTECTED] | [EMAIL PROTECTED] `- people.debian.org/~aurel32 | www.aurel32.net
