[uml-devel] Debug uml kernel won't boot (VFS: Unable to mount root fs)

[uml-devel] Debug uml kernel won't boot (VFS: Unable to mount root fs)

[Joydeep Sen Sarma]

Hi folks,

The regular uml kernel worked fine till i turned
on the debug option. Kernel version is 2.4.22 and
I applied uml patch 2.4.22-6 to it. Root file System
is the Debian-3.0r0.ext2.bz2 image from uml home page.

# ls -l root_fs
-rw-r--r--    1 root     root     62862336 Dec 14
18:06 root_fs
# ./linux ubd0=root_fs debug gdb-pid=2646

From debugger, failure happens here:

Breakpoint 3, do_kern_mount (fstype=0xa194b000 "ext2",
flags=32769, 
    name=0xa1949000 "/dev/root", data=0x0) at
super.c:793
(gdb)
get_sb_bdev (fs_type=0xa01fb930, flags=-12,
dev_name=0xa1949000 "/dev/root", 
    data=0x0) at super.c:669

this call in get_sb_nodev fails:
	error = path_lookup(dev_name,
LOOKUP_FOLLOW|LOOKUP_POSITIVE, &nd);

with err code of ENOENT. Any ideas what's wrong or
how I can debug this ? (I have tried the 
root=/dev/ubd/0 option - same result)

thanks,

Joydeep




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Re: [uml-devel] Debug uml kernel won't boot (VFS: Unable to mount root fs)

[Henrik Nordstrom]

You need to use root=... to specify which device or partition the root is
on. The ubd0 argument just connects the ubda device to the specified file,
it does not specify that the root is there.

Regards
Henrik


On Mon, 15 Dec 2003, Joydeep Sen Sarma wrote:

> Hi folks,
> 
> The regular uml kernel worked fine till i turned
> on the debug option. Kernel version is 2.4.22 and
> I applied uml patch 2.4.22-6 to it. Root file System
> is the Debian-3.0r0.ext2.bz2 image from uml home page.
> 
> # ls -l root_fs
> -rw-r--r--    1 root     root     62862336 Dec 14
> 18:06 root_fs
> # ./linux ubd0=root_fs debug gdb-pid=2646
> 
> >From debugger, failure happens here:
> 
> Breakpoint 3, do_kern_mount (fstype=0xa194b000 "ext2",
> flags=32769, 
>     name=0xa1949000 "/dev/root", data=0x0) at
> super.c:793
> (gdb)
> get_sb_bdev (fs_type=0xa01fb930, flags=-12,
> dev_name=0xa1949000 "/dev/root", 
>     data=0x0) at super.c:669
> 
> this call in get_sb_nodev fails:
> 	error = path_lookup(dev_name,
> LOOKUP_FOLLOW|LOOKUP_POSITIVE, &nd);
> 
> with err code of ENOENT. Any ideas what's wrong or
> how I can debug this ? (I have tried the 
> root=/dev/ubd/0 option - same result)
> 
> thanks,
> 
> Joydeep
> 
> 
> 
> 
> __________________________________
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Re: [uml-devel] Debug uml kernel won't boot (VFS: Unable to mount root fs)

[Joydeep Sen Sarma]

as i mentioned - i have already tried the
root=/dev/ubd/0 option and that doesn't work too.
In any case, non-debug kernel works without root
option,

Joydeep

--- Henrik Nordstrom <hno@marasystems.com> wrote:
> You need to use root=... to specify which device or
> partition the root is
> on. The ubd0 argument just connects the ubda device
> to the specified file,
> it does not specify that the root is there.
> 
> Regards
> Henrik
> 
> 
> On Mon, 15 Dec 2003, Joydeep Sen Sarma wrote:
> 
> > Hi folks,
> > 
> > The regular uml kernel worked fine till i turned
> > on the debug option. Kernel version is 2.4.22 and
> > I applied uml patch 2.4.22-6 to it. Root file
> System
> > is the Debian-3.0r0.ext2.bz2 image from uml home
> page.
> > 
> > # ls -l root_fs
> > -rw-r--r--    1 root     root     62862336 Dec 14
> > 18:06 root_fs
> > # ./linux ubd0=root_fs debug gdb-pid=2646
> > 
> > >From debugger, failure happens here:
> > 
> > Breakpoint 3, do_kern_mount (fstype=0xa194b000
> "ext2",
> > flags=32769, 
> >     name=0xa1949000 "/dev/root", data=0x0) at
> > super.c:793
> > (gdb)
> > get_sb_bdev (fs_type=0xa01fb930, flags=-12,
> > dev_name=0xa1949000 "/dev/root", 
> >     data=0x0) at super.c:669
> > 
> > this call in get_sb_nodev fails:
> > 	error = path_lookup(dev_name,
> > LOOKUP_FOLLOW|LOOKUP_POSITIVE, &nd);
> > 
> > with err code of ENOENT. Any ideas what's wrong or
> > how I can debug this ? (I have tried the 
> > root=/dev/ubd/0 option - same result)
> > 
> > thanks,
> > 
> > Joydeep
> > 
> > 
> > 
> > 
> > __________________________________
> > Do you Yahoo!?
> > New Yahoo! Photos - easier uploading and sharing.
> > http://photos.yahoo.com/
> > 
> > 
> >
>
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> 


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Re: [uml-devel] Debug uml kernel won't boot (VFS: Unable to mount root fs)

[Jeff Dike]

jsensarma@yahoo.com said:
> The regular uml kernel worked fine till i turned on the debug option.
> Kernel version is 2.4.22 and I applied uml patch 2.4.22-6 to it.

jjohnson@eclipse.ncsc.mil said:
> When I try to run a UML kernel as root, using a real partition as the
> UML root  filesystem, it reports that the filesystem is corrupted and
> goes into single  user mode.
>
> The UML kernel is 2.4.22 with uml-patch-2.4.22-6 applied.

For grins, can you try 2.4.22-5 and see if it's any better?  Looking through
my mail I see a couple of complaints about things newly broken in -6 and
I'd like to see if these are some more.

				Jeff



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Re: [uml-devel] Debug uml kernel won't boot (VFS: Unable to mount root fs)

[Joydeep Sen Sarma]

Well - somewhere between switching from the non-debug
to the debug kernel, my .config got completely hosed.
ubd driver was not enabled - neither was pty channel.
Ultimately i just copied over a fresh source tree and
then everything was fine.

I don't know how i got into this mess. perhaps i 
omitted ARCH=um one of the times on the make 
commandline. Don't know ..

thanks,

Joydeep



--- Jeff Dike <jdike@addtoit.com> wrote:
> jsensarma@yahoo.com said:
> > The regular uml kernel worked fine till i turned
> on the debug option.
> > Kernel version is 2.4.22 and I applied uml patch
> 2.4.22-6 to it.
> 
> jjohnson@eclipse.ncsc.mil said:
> > When I try to run a UML kernel as root, using a
> real partition as the
> > UML root  filesystem, it reports that the
> filesystem is corrupted and
> > goes into single  user mode.
> >
> > The UML kernel is 2.4.22 with uml-patch-2.4.22-6
> applied.
> 
> For grins, can you try 2.4.22-5 and see if it's any
> better?  Looking through
> my mail I see a couple of complaints about things
> newly broken in -6 and
> I'd like to see if these are some more.
> 
> 				Jeff
> 


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