[PATCH] make 2.5.49 mount root again for devfs users

[PATCH] make 2.5.49 mount root again for devfs users

[Helge Hafting]

init/do_mounts.c changed in 2.5.48, and booting with devfs
(and without initial ramdisk) has been impossible since then.  
I experimented with do_mounts undoing the early devfs mount.  
Devfs is mounted later anyway.

Feel free to test, but be warned that I am not an expert
on this part of the kernel.  This made 2.5.49 work for
me though.  I hope someone can comment on this.
If it isn't "the right way" please tell what is.

Helge Hafting


--- do_mounts.c.original        2002-11-25 12:41:48.000000000 +0100
+++ do_mounts.c 2002-11-25 13:34:58.000000000 +0100
@@ -846,10 +846,7 @@
 {
        int is_floppy;
 
-#ifdef CONFIG_DEVFS_FS
-       sys_mount("devfs", "/dev", "devfs", 0, NULL);
-       do_devfs = 1;
-#endif
+
 
        md_run_setup();

Re: [PATCH] make 2.5.49 mount root again for devfs users

[Helge Hafting]

>Does your patch break being able to mount root with things 
>like "root=/dev/discs/disc0/part9" 
>and/or "root=/dev/scsi/host0/bus0/id0/lun0/part9"?  For people with devfs 
>enable kernels those are valid boot entries and should not end up getting 
>broken needlessly.

I have devfs, and my /etc/lilo.conf contains this:

boot=/dev/ide/host0/bus0/target0/lun0/disc
root=/dev/ide/host0/bus0/target0/lun0/part4

I haven't tried to put this in a command line
option, but it works fine from lilo.

The reason fro the patch is that I couldn't boot
with devfs anymore, I'd get a 
"panic: couldn't mount root at 03:04"
or similiar, depending on which machine I used.

Now I don't get that, it just works.

Have you been able to boot a devfs-enabled
2.5.48 or later?  On a machine where /dev
is only a empty directory - a mountpoint
for devfs use?



Helge Hafting

Re: [PATCH] make 2.5.49 mount root again for devfs users

[Mohamed El Ayouty]

Ok, what I experienced is if I configured the kernel with:

CONFIG_UNIX98_PTYS = Y
CONFIG_DEVFS_FS = Y
CONFIG_DEVFS_MOUNT = Y

everything works correctly, but if I configure with only:

CONFIG_UNIX98_PTYS = N
CONFIG_DEVFS_FS = Y
CONFIG_DEVFS_MOUNT = Y

it gives me a panic:

VFS: Cannot open root device "hda2" or 03:02
Please append a correct "root=" boot option
Kernel panic: VFS: Unable to mount root fs on 03:02

Hope this helps

Mohamed

Re: [PATCH] make 2.5.49 mount root again for devfs users

[Milton Miller]

What you did was bypass devfs, and cause create_dev to mknod a file
with the device number of your root instead of creating a symlink
to the normal devfs node.

Is your booter translating the device name into a number?  You can
check this by looking at the printed comand line in the dmesg, or
by cat /proc/cmdline .

If you see root=0304 then your booter is translating the device number
and therefore find_in_devfs is failing (possibly because of the previously
metioned patch to read_dir).

I notice that there are lots of hardcoded maxdepth of 64 characters for
the devfs path, but yours seems to be 39 and therefore should be ok.

milton