Re: mem=16MB laptop testing

[Andrew Morton <akpm@osdl.org>]

Russell King <rmk+lkml@arm.linux.org.uk> wrote:
>
> On Tue, Oct 14, 2003 at 05:10:31AM -0700, Andrew Morton wrote:
> > Russell King <rmk+lkml@arm.linux.org.uk> wrote:
> > > On Tue, Oct 14, 2003 at 04:56:14AM -0700, Andrew Morton wrote:
> > > > I guess not mounting /sys doesn't help here.  It would be nice.  Maybe with
> > > > a CONFIG_I_WILL_NEVER_MOUNT_SYSFS we could avoid all those allocations.
> > > 
> > > I believe sysfs is required for mounting the root filesystem - see
> > > name_to_dev_t in init/do_mounts.c.
> > 
> > OK.  But it looks like if /sys is empty and you provide "root=03:02" then
> > things will still work.  It's a matter of trying it...
> 
> Uhh?
> 
> dev_t name_to_dev_t(char *name)
> {
>         dev_t res = 0;
> 
>         sys_mkdir("/sys", 0700);
>         if (sys_mount("sysfs", "/sys", "sysfs", 0, NULL) < 0)
>                 goto out;
> 
> 	...
> 
> out:
>         sys_rmdir("/sys");
>         return res;
> }
> 
> If sysfs can't be mounted, then it looks like we can't even decode a
> numeric major:minor root device specification.

Well I was proposing that sysfs be present and mountable, but empty.  ie:
make sysfs_create() a no-op.  Something like that.  Additional touchups may
be needed of course.