On Thu, Jun 05, 2014 at 11:49:49PM +0200, Richard Weinberger wrote: > Am 05.06.2014 06:15, schrieb Honggang Li: > > arch/x86/um/checksum_32.S had been copy & paste from x86. When build > > x86 uml, csum_partial_copy_generic_i386 mess up the exception table. > > In fact, exception table dose not work in uml kernel. > > Are you sure that exception tables do not work on UML? > I said, I'm not sure. Can you please find out?
Hi, After traced i386 uml kernel with gdb , I'm sure exception tables do *not* work. When csum_partial_copy_generic_i386 read user space memory, an access error exception arises, however, the segv function always return zero. So, the fixup nerver executed. The uml system hang (not kernel panic). thanks. > > In arch/um/kernel/trap.c:segv() we have the mechanism for it: > else if (!is_user && arch_fixup(ip, regs)) > goto out; > > The interesting question is, is this by design or was it just copy&pasted > from x86 > many moons ago? :) > > > And csum_partial_copy_generic_i386 never been called. So, delete it. > > I like such clean ups. :-) > > Thanks, > //richard ------------------------------------------------------------------------------ HPCC Systems Open Source Big Data Platform from LexisNexis Risk Solutions Find What Matters Most in Your Big Data with HPCC Systems Open Source. Fast. Scalable. Simple. Ideal for Dirty Data. Leverages Graph Analysis for Fast Processing & Easy Data Exploration http://p.sf.net/sfu/hpccsystems _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
