root=/dev/mtdblock doesn't work with kernel 2.4.18

root=/dev/mtdblock doesn't work with kernel 2.4.18

[Stephan Linke]

Hi!

After changing from 2.4.8-pre4 to a 2.4.18 kernel I can't mount the flash as
root device any more. I'm using the "root=" boot argument to do so.
The filesystem (cramfs) is alredy detected in mount_root() (super.c) when
mount_root calls blkdev_put(bdev, BDEV_FS); Which for some reasons has to
call the release function of the device which results in mtdblock_release()
being called. The hole thing stops when invalidate_device() calls
fsync_dev(dev). Where we'll shurely get back to the MTD driver (some how).
Calling blk_dev_get() and blk_dev_put() in mount_root() is a difference
between both kernel versions. But removing that change simply leades to
another problem...

Everything works fine when running with NFS as rootfs mounting the flash
with /etc/fstab. So it looks like this is some kind of race condition.

Maybe this is an issue to the FS people. But you should have experience with
using the rootfs that way.

Thanks, Stephan


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Re: root=/dev/mtdblock doesn't work with kernel 2.4.18

[David Woodhouse]

On Tue, 19 Mar 2002, Stephan Linke wrote:

> After changing from 2.4.8-pre4 to a 2.4.18 kernel I can't mount the flash as
> root device any more. I'm using the "root=" boot argument to do so.
> The filesystem (cramfs) is alredy detected in mount_root() (super.c) when
> mount_root calls blkdev_put(bdev, BDEV_FS); Which for some reasons has to
> call the release function of the device which results in mtdblock_release()
> being called. The hole thing stops when invalidate_device() calls
> fsync_dev(dev).

Remove just the call to invalidate_device() in mtdblock_release()

-- 
dwmw2

RE: root=/dev/mtdblock doesn't work with kernel 2.4.18

[Stephan Linke]

Thank's David! Now it works.

>
> > After changing from 2.4.8-pre4 to a 2.4.18 kernel I can't mount the
flash as
> > root device any more. I'm using the "root=" boot argument to do so.
> > The filesystem (cramfs) is alredy detected in mount_root() (super.c)
when
> > mount_root calls blkdev_put(bdev, BDEV_FS); Which for some reasons has
to
> > call the release function of the device which results in
mtdblock_release()
> > being called. The hole thing stops when invalidate_device() calls
> > fsync_dev(dev).
>
> Remove just the call to invalidate_device() in mtdblock_release()
>
> --
> dwmw2
>