On Wed, Jul 27, 2011 at 02:55:06PM +0200, Michael Holzheu wrote: > From: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> > > On s390 we do not create page tables at all for the crashkernel memory. > This requires a s390 specific version for kimage_load_crash_segment(). > Therefore this patch declares this function as "__weak". The s390 version is > very simple. It just copies the kexec segment to real memory without using > page tables: > > int kimage_load_crash_segment(struct kimage *image, > struct kexec_segment *segment) > { > return copy_from_user_real((void *) segment->mem, segment->buf, > segment->bufsz); > } > > There are two main advantages of not creating page tables for the > crashkernel memory: > > a) It saves memory. We have scenarios in mind, where crashkernel > memory can be very large and saving page table space is important. > b) We protect the crashkernel memory from being overwritten. > > Signed-off-by: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> > --- > kernel/kexec.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > --- a/kernel/kexec.c > +++ b/kernel/kexec.c > @@ -842,8 +842,8 @@ out: > return result; > } > > -static int kimage_load_crash_segment(struct kimage *image, > - struct kexec_segment *segment) > +int __weak kimage_load_crash_segment(struct kimage *image, > + struct kexec_segment *segment) A comment here why we are making it weak should help in increasing the code readability. Thanks Vivek > { > /* For crash dumps kernels we simply copy the data from > * user space to it's destination. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html