Jan> So you have two options. Either make your bootloader load it (it
Jan> should be able to if it knows about "multiboot specification") or
Jan> turn the FAT16 partition into kind of initrd - the pivot_root
Jan> syscall is not limited to be used from ramdisk.
OK, I'm going for option two. I think it is perfect. I'm having
trouble with my pivot_root. I've included my program below. This is
a cleaned-up version of the program, the original did a whole bunch of
error checking to confirm that the open, ioctl, close, mount, chdir,
and pivot_root calls don't return errors. The kernel prints:
EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended
GOT HEREKernel panic: Attempted to kill init!
What's up with that?
Thanks,
Dave
/**
*** linuxrc.c: Mount /initrd.bin loopback as cramfs and pivot_root to it
***
*** Usage:
*** vmlinux init=linuxrc
***
*** David Wuertele Tue May 20 16:14:35 2003
***
**/
#include <fcntl.h>
#include <stdio.h>
#include <linux/posix_types.h>
#undef dev_t
#define dev_t __kernel_dev_t
#include <linux/loop.h>
#undef dev_t
int
main (int argc, char *const argv[])
{
struct loop_info loopinfo;
int fd, ffd;
ffd = open ("/initrd.bin", O_RDWR);
fd = open ("/dev/loop/0", O_RDWR);
memset (&loopinfo, 0, sizeof(loopinfo));
strncpy (loopinfo.lo_name, "/initrd.bin", LO_NAME_SIZE);
loopinfo.lo_offset = 0;
loopinfo.lo_encrypt_key_size = 0;
ioctl (fd, LOOP_SET_FD, ffd);
ioctl (fd, LOOP_SET_STATUS, &loopinfo);
close (fd);
close (ffd);
mount ("/dev/loop/0", "/mnt", "ext2", 0, NULL);
chdir ("/mnt");
pivot_root ("/mnt", "/mnt/tmproot");
fprintf (stderr, "GOT HERE\n");
execv ("/sbin/init", argv);
return 0;
}
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