On Thu, Apr 08, 2010 at 12:46:44PM -0400, Neil Horman wrote: > 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 Hi Neil, This seems reasonable to me. > Tested successfully by myself > Originally-authored-by: Dave Anderson <anderson at redhat.com> > Signed-off-by: Neil Horman <nhorman at tuxdriver.com> > > diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c > index 9d37442..85879a9 100644 > --- a/kexec/arch/i386/crashdump-x86.c > +++ b/kexec/arch/i386/crashdump-x86.c > @@ -114,6 +114,15 @@ 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 >= 0x1000000000) > + continue; > + if (end >= 0x1000000000) > + end = 0xfffffffff; > + Nit picking... Might it be better to use 0xfffffffff (or 0x1000000000) consistently? if (start > 0xfffffffff) continue; if (end > 0xfffffffff) end = 0xfffffffff; Or even make 0xfffffffff (or 0x1000000000) a #define ? > crash_memory_range[memory_ranges].start = start; > crash_memory_range[memory_ranges].end = end; > crash_memory_range[memory_ranges].type = type; > > > _______________________________________________ > kexec mailing list > kexec at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec
