On Wed, Jun 02, 2010 at 01:16:01PM -0400, John David Anglin wrote: > On Wed, 02 Jun 2010, Modestas Vainius wrote: > > > Hello, > > > > this bug [1] is back to the "very common" department with eglibc 2.11 (libc6- > > dev_2.11.1-1) builds. Majority of KDE applications are failing to build on > > hppa again. Is there really nothing what could be done to fix it? > > I will just say it is very tricky. I think a fix is possible (arm and mips > had similar cache problems) but the victim replacement present in PA8800/PA8900 > caches makes the problem especially difficult for hardware using these > processors. > > I have spent the last few months testing various alternatives and have > now done hundreds of kernel builds. I did post some experimental patches > that fix the problem on UP kernels. However, the problem is not resolved > for SMP kernels. Note that Debian's buildds run a UP kernel, so as soon as those fixes go upstream we can pull them in. Thanks for all your work here! > The minifail test is a good one to demonstrate the problem. Indeed, > a very similar test was given in the thread below: > http://readlist.com/lists/vger.kernel.org/linux-kernel/54/270861.html > > This thread also discusses the PA8800 problem: > http://readlist.com/lists/vger.kernel.org/linux-kernel/54/271417.html > > I currently surmise that we have a problem with the cache victim > replacement, although the cause isn't clear. I did find recently > that the cache prefetch in copy_user_page_asm extends to the line > beyond the end of the page, but fixing this doesn't resolve the problem. > > I am still experimenting with using equivalent aliasing. It does > help to flush in ptep_set_wrprotect. > > Dave -- dann frazier -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
