System fails to acknowledge changing of SD when rootfs is on a different device.

Status changed to 'Confirmed' because the bug affects multiple users.

in the omap3 world, everything is fine (both our omap3 kernel and linaro-omap):

flag@omap:~$ uname -a
Linux omap 3.0.0-11-omap #18 Mon Sep 19 14:55:51 CEST 2011 armv7l armv7l armv7l GNU/Linux
flag@omap:~$ dmesg | grep mmc
[ 4.408660] mmc0: host does not support reading read-only switch. assuming write-enable.
[ 4.425048] mmc0: new SDHC card at address e624
[ 4.434051] mmcblk0: mmc0:e624 SU04G 3.69 GiB
[ 4.454132] mmcblk0: p1 p2

remove the micro sd card:

[ 198.081451] mmc0: card e624 removed

reinsert it:

[ 214.931762] mmc0: host does not support reading read-only switch. assuming write-enable.
[ 214.948913] mmc0: new SDHC card at address e624
[ 214.972625] mmcblk0: mmc0:e624 SU04G 3.69 GiB
[ 214.992828] mmcblk0: p1 p2

flag@omap:~$ sudo mount /dev/mmcblk0p1 /mnt/
flag@omap:~$ ls -la /mnt/
total 17498
drwxr-xr-x 2 root root 1024 1970-01-01 01:00 .
drwxr-xr-x 22 root root 4096 2011-09-20 17:22 ..
-rwxr-xr-x 1 root root 230 2011-09-20 17:16 boot.cmd
-rwxr-xr-x 1 root root 302 2011-09-20 17:17 boot.scr
-rwxr-xr-x 1 root root 302 2011-09-20 17:23 boot.scr.bak
-rwxr-xr-x 1 root root 379 2011-09-20 17:01 boot.scr.orig
-rwxr-xr-x 1 root root 23936 2011-08-30 05:14 MLO
-rwxr-xr-x 1 root root 292408 2011-08-30 05:14 u-boot.bin
-rwxr-xr-x 1 root root 3740176 2011-09-20 17:23 uImage
-rwxr-xr-x 1 root root 3740176 2011-09-20 17:23 uImage.bak
-rwxr-xr-x 1 root root 4472862 2011-09-20 17:23 uInitrd
-rwxr-xr-x 1 root root 5638988 2011-09-20 17:23 uInitrd.bak

while on omap4, the kernel (neither oneiric/ti-omap4 nor linux-linaro-omap) doesn't sense the sd card change at all:

flag@omap:~$ uname -a
Linux omap 3.0.0-1004-linaro-omap #6 SMP PREEMPT Tue Sep 13 14:08:42 UTC 2011 armv7l armv7l armv7l GNU/Linux
flag@omap:~$ dmesg | grep mmc
[ 4.376831] mmc0: host does not support reading read-only switch. assuming write-enable.
[ 4.395568] mmc0: new SDHC card at address 1234
[ 4.434814] mmcblk0: mmc0:1234 SA04G 3.68 GiB
[ 4.452484] mmcblk0: p1 p2
flag@omap:~$ ls -la /dev/mmcblk0*
brw-rw---- 1 root disk 179, 0 2011-09-20 18:22 /dev/mmcblk0
brw-rw---- 1 root disk 179, 1 2011-09-20 18:22 /dev/mmcblk0p1
brw-rw---- 1 root disk 179, 2 2011-09-20 18:22 /dev/mmcblk0p2
flag@omap:~$

remove card:

# nothing is printed on console!!!
flag@omap:~$ ls -la /dev/mmcblk0*
brw-rw---- 1 root disk 179, 0 2011-09-20 18:22 /dev/mmcblk0
brw-rw---- 1 root disk 179, 1 2011-09-20 18:22 /dev/mmcblk0p1
brw-rw---- 1 root disk 179, 2 2011-09-20 18:22 /dev/mmcblk0p2

and he it thinks it's still there!!!

reinsert the sd card:

# again no output on console

flag@omap:~$ sudo mount /dev/mmcblk0p1 /mnt/
mount: /dev/mmcblk0p1: can't read superblock

on console:
...
[ 354.103424] mmcblk0: error -110 sending status command
[ 354.108673] mmcblk0: error -110 sending read/write command, response 0x0, card status 0x0
[ 354.117492] mmcblk0: error -110 transferring data, sector 68, nr 3, card status 0x0
[ 354.125579] end_request: I/O error, dev mmcblk0, sector 68
[ 354.131469] mmcblk0: error -110 sending status command
[ 354.136718] mmcblk0: error -110 sending read/write command, response 0x0, card status 0x0
[ 354.145599] mmcblk0: error -110 transferring data, sector 69, nr 2, card ...

try this kernel:

http://people.canonical.com/~ppisati/linux-image-3.0.0-1204-omap4_3.0.0-1204.9~mmcswapfix_armel.deb

Did the kernel mentioned in comment #5 resolve this issue?

Migrated to bugzilla: https://bugs.linaro.org/show_bug.cgi?id=553