On Mon, Oct 19, 2015 at 11:32:58AM +0200, Andreas Fenkart wrote: > Hi Simon, > > 2015-10-16 3:30 GMT+02:00 Simon Horman <horms at verge.net.au>: > > On Fri, Oct 09, 2015 at 03:27:18PM +0200, Andreas Fenkart wrote: > >> starting 'kexec -l /dev/mmcblk0p1' fails since the size of > >> a block device can not be determined with stat > > > > Could you provide some motivation for kexec reading a kernel image > > from a block device as per the example above? > > We plan to use it for our embedded system > > We have an interim initramfs, that selects the kernel we want to boot > our real system. Something like a n+1 stage boot loader, > where n is the last stage of u-boot. The motivation is to do a safe > kernel upgrade on the production rootfs through package management. > The new kernel is dropped into a folder where the interim system will > selects the kernel with the highest priority. No reconfiguration of > u-boot/rescue system needed. In case no kernel has yet been installed, > we fall back to the factory default, which is installed in a raw flash > partition on eMMC without filesystem. > > https://git.digitalstrom.org/bsp/dss-rescue-tools/blob/master/src/kernel-fallback-dss11-1gb-t1.config Nice :) > >> Signed-off-by: Andreas Fenkart <andreas.fenkart at dev.digitalstrom.org> > >> --- > >> kexec/kexec.c | 10 ++++++++++ > >> 1 file changed, 10 insertions(+) > >> > >> diff --git a/kexec/kexec.c b/kexec/kexec.c > >> index ff024f3..8b8846e 100644 > >> --- a/kexec/kexec.c > >> +++ b/kexec/kexec.c > >> @@ -26,7 +26,9 @@ > >> #include <stdlib.h> > >> #include <errno.h> > >> #include <limits.h> > >> +#include <sys/ioctl.h> > >> #include <sys/mman.h> > >> +#include <sys/mount.h> > >> #include <sys/types.h> > >> #include <sys/stat.h> > >> #include <sys/reboot.h> > >> @@ -554,6 +556,14 @@ char *slurp_file(const char *filename, off_t *r_size) > >> die("Can not seek to the begin of file %s: %s\n", > >> filename, strerror(errno)); > >> buf = slurp_fd(fd, filename, size, &nread); > >> + } else if (S_ISBLK(stats.st_mode)) { > >> + /* taken from blockdev */ > > > > Is "blockdev" Linux kernel code? > > It is a util-linux tool, which is GPL of course. I added the comment > as a reference, since I couldn't find a man page for BLKGETSIZE64. > Since it's a straight forward ioctl call, there is probably no > copyright violation at all, and I could well remove it. Understood. Could you repost with the blockdev comment removed? > >> + unsigned long long llu = -1; > >> + err = ioctl(fd, BLKGETSIZE64, &llu); > >> + if (err < 0) > >> + die("Can't retrieve size of block device %s: %s\n", > >> + filename, strerror(errno)); > >> + size = llu; > >> } else { > >> size = nread = stats.st_size; > >> buf = mmap(NULL, size, > >> -- > >> 2.5.1 > >> > >> > >> _______________________________________________ > >> kexec mailing list > >> kexec at lists.infradead.org > >> http://lists.infradead.org/mailman/listinfo/kexec > >> >
