On Fri, Apr 09, 2010 at 09:41:11AM -0400, Vivek Goyal wrote: > On Fri, Apr 09, 2010 at 08:17:49AM -0400, Neil Horman wrote: > > Version 2, with Simons consistency fixes and cleanups > > > > Fix up x86 kexec to exclude memory on i686 kernels beyond 64GB limit > > > > We found a problem recently on x86 systems. If a 32 bit PAE enabled system > > contains more then 64GB of physical ram, the kernel will truncate the max_pfn > > value to 64GB. Unfortunately it still leaves all the physical memory regions > > present in /proc/iomem. Since kexec builds its elf headers based on > > /proc/iomem the elf headers indicate the size of memory is larger than what the > > kernel is willing to address. The result is that, during a copy of > > /proc/vmcore, a read will return -EFAULT when the requested offset is beyond the > > 64GB range, leaving the seemingly truncated vmcore useless, as the elf headers > > indicate memory beyond what the file contains. > > > > The fix for it is pretty straightforward, just ensure that, when on x86 systems, > > we don't record any entries in the memory_range array that cross the 64Gb mark. > > This keeps us in line with the kernel and lets the copy finish sucessfully, > > providing a workable core > > > > Tested successfully by myself > > Originally-authored-by: Dave Anderson <anderson at redhat.com> > > Signed-off-by: Neil Horman <nhorman at tuxdriver.com> > > > > > > crashdump-x86.c | 15 +++++++++++++++ > > 1 file changed, 15 insertions(+) > > > > diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c > > index 9d37442..9d35b3e 100644 > > --- a/kexec/arch/i386/crashdump-x86.c > > +++ b/kexec/arch/i386/crashdump-x86.c > > @@ -34,6 +34,12 @@ > > #include "crashdump-x86.h" > > #include <x86/x86-linux.h> > > > > +/* > > + * This defines the the last address that we can support access to > > + * with a PAE enabled kernel > > + */ > > +#define 64G_LIMIT 0xfffffffff > > + > > extern struct arch_options_t arch_options; > > > > /* Forward Declaration. */ > > @@ -114,6 +120,15 @@ static int get_crash_memory_ranges(struct memory_range **range, int *ranges, > > if (end <= 0x0009ffff) > > continue; > > > > + /* > > + * Exclude any segments starting at or beyond 64GB, and > > + * restrict any segments from ending at or beyond 64GB. > > + */ > > + if (start > 64GB_LIMIT) > > + continue; > > + if (end > 64GB_LIMIT) > > + end = 64GB_LIMIT; > > + > > Looks good to me. > > Acked-by: Vivek Goyal <vgoyal at redhat.com> Thanks Neil. Thanks Vivek. Thanks Dave. Applied :-)
