On Fri, May 7, 2010 at 1:38 PM, Paul Mackerras <pau...@samba.org> wrote: > On Thu, May 06, 2010 at 12:28:44PM +0800, Li Yang wrote: > >> The root cause of this oops might not be related with the vmalloc'ed >> area processing in Instruction Storage Interrupt. But x86 does have >> the code for processing it while we don't. Is it because we have >> nothing to do with the vmalloc'ed ISI on PowerPC architecture? > > On PowerPC we always read the kernel page tables rooted at > swapper_pg_dir to get translations for kernel addresses (those above > KERNELBASE). We can do that because it is kernel code (software) that > reads the Linux page tables. On x86, it is hardware that reads the > Linux page tables, and it always reads the page tables for the current > process. This means that the kernel part of each process's page > tables needs to contain copies of all the kernel PTEs on x86. To > avoid having to set a PTE in every process's page tables when doing a > vmalloc or ioremap, x86 just creates them in swapper_pg_dir and then > creates them on demand in each process's page tables as needed. > That's why they have code to handle vmalloc faults in their page fault > handler.
Thanks a lot for the explanation. - Leo _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
