On Fri, Apr 09, 2010 at 08:32:48AM +1000, Simon Horman wrote: > 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; > Not sure what you mean by consistent here? It seems we are using it consistently in this patch. Or are you referring to updating the function as a whole? > Or even make 0xfffffffff (or 0x1000000000) a #define ? Yeah, that makes sense. If you can clarify your above point on consistency, I can repost. thanks Neil > > > 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 >
