On Friday 10 July 2009, Frans Pop wrote: > On Thu, 9 Apr 2009, Linus Torvalds wrote: > > On Thu, 9 Apr 2009, Andrew Morton wrote: > > > -fwrapv killed Barry's gcc-4.1.2-compiled kernel in 2.6.27.x, > > > 2.6.28.x and presumably 2.6.29, 2.6.30. > > > > Auughh. I hate compiler bugs. They're horrible to debug. > > > > I _think_ 'fwrapv' only really matters with gcc-4.3, so maybe we > > could just enable it for new versions. > > > > HOWEVER, I also wonder if we could instead of "-fwrapv" use > > "-fno-strict-overflow". They are apparently subtly different, and > > maybe the bug literally only happens with -fwrapv. > > > > Barry, can you see if that simple "replace -fwrapv with > > -fno-strict-overflow" works for you? Prompted by the same suggestion from Ben Hutchings I checked this too, but -fno-strict-overflow was only introduced in gcc 4.2. So using it instead of -fwrapv *would* fix the problem for gcc 4.1, but *only* because it would effectively do the same as the patch I proposed: not add an option at all for gcc 4.1. So that change seems illogical unless there are other reasons to prefer -fno-strict-overflow over -fwrapv (well, it would avoid the gcc version check). It does however make it somewhat more logical to change the test in my proposed patch to also allow -fwrapv for gcc 4.2. Cheers, FJP -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
