3.17-rc2: root=/dev/mmcblk0p2 command line parsing fails

From: Pavel Machek
Date: Tue Aug 26 2014 - 07:47:16 EST


Hi!

> > > mmc0: new SDHC card at address b368
> > > mmcblk0: mmc0:b368 USD 7.45 GiB
> > > mmcblk0: p1 p2 p3 p4
> > > VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error
> > > -6
> > > Please append a correct "root=" boot option; here are the available
> > > partitions:
> > > b300 7822336 mmcblk0 driver: mmcblk
> > > b301 102400 mmcblk0p1 00082434-01
> > > b302 1048576 mmcblk0p2 00082434-02
> > > b303 1024 mmcblk0p3 00082434-03
> > > b304 6086656 mmcblk0p4 00082434-04
> > > Kernel panic - not syncing: VFS: Unable to mount root fs on
> > > unknown-block(0,0)
> > > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.16.0-11208-gef74117-dirty
> > > #2
> >
> > Hmm...today's tip-top(899552d6) and ba36899 booted just fine for me. I
> > noticed something, you must have commits on top of your ba36899? Mine
> > shows 3.16.0-11149-gba36899.
>
> Ok, thanks for info. I went back to 3.16, and it worked in same
> config, and went to 3.17, and it broke.

The problem is still there in 3.17-rc2. 3.16 does not have the
problem. Messages are still similar:

mmc0: new high speed SDHC card at address b368
mmcblk0: mmc0:b368 USD 7.45 GiB
mmcblk0: p1 p2 p3 p4
VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error
-6
Please append a correct "root=" boot option; here are the available
partitions:
b300 7822336 mmcblk0 driver: mmcblk
b301 102400 mmcblk0p1 00082434-01
b302 1048576 mmcblk0p2 00082434-02
b303 1024 mmcblk0p3 00082434-03
b304 6086656 mmcblk0p4 00082434-04
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
CPU: 0 PID: 1 Comm: swapper/0 Not tainted
3.17.0-rc2-00368-gec0400b-dirty #83


What is going on there? Clearly partition table was parsed and
partitions are available; does the mention of unknown-block(0,0) mean
that kernel failed to parse the command line?

I replaced "root=/dev/mmcblk0p2" with "root=b302" and have a booting
system.

Pavel

--
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