linux-2.6.36-rc4 problems booting rootfs from SD card

[d.cristiani@idem-tech.it (dylan cristiani)]

Hi sirs, here is my scenario: kernel 2.6.36-rc4; cpu pxa270; platform
is an enhancement (i like to see things that way...) and customisation
of the mainstone III board; here comes the (my) problem: if i boot with
my standard kernel boot command line (to boot from system flash):
'root=/dev/mtdblock2 rootfstype=jffs2 mem=64M console=ttyS0,115200n8'

i can get the rootfs up, and the SD card is up too, and correctly
working; here's the relevant kernel log:

....
XScale iWMMXt coprocessor detected.
 rtc-ds1307 0-0068: setting system clock to 2010-09-28 03:03:08 UTC
(1285642988)
 pxa27x-udc pxa27x-udc: USB reset
 mmc0: new SD card at address aaaa
 mmcblk0: mmc0:aaaa SD02G 1.84 GiB
  mmcblk0: p1
 pxa27x-udc pxa27x-udc: USB reset
.....

then the rootfs coems up properly.

Else, if i try to boot the rootfs directly form the SD card, with
kernel boot command line:
'root=/dev/mmcblk0p1 rootfstype=ext2 mem=64M console=ttyS0,115200n8'

the rootfs doen't work, and i can see some problems around with usb
client gadget; here's the relevant kernel log:

....
XScale iWMMXt coprocessor detected.
 rtc-ds1307 0-0068: setting system clock to 2010-09-28 03:03:43 UTC
(1285643023)
 VFS: Cannot open root device "mmcblk0p1" or unknown-block(0,0)
 Please append a correct "root=" boot option; here are the available
partitions:
 1f00             256 mtdblock0 (driver?)
 1f01            2048 mtdblock1 (driver?)
 1f02           63232 mtdblock2 (driver?)
 Kernel panic - not syncing: VFS: Unable to mount root fs on
unknown-block(0,0)
 Backtrace:
 [] (dump_backtrace+0x0/0x118) from [] (dump_stack+0x18/0x1c)
r6:00008000 r5:c3813000 r4:c0417b70 r3:c03f5714
 [] (dump_stack+0x0/0x1c) from [] (panic+0x60/0x18c)
 [] (panic+0x0/0x18c) from [] (mount_block_root+0x25c/0x2ac)
 pxa27x-udc pxa27x-udc: ep0:handle_ep0: state=WAIT_FOR_SETUP,
req=(null), udccsr0=0x2c1, udcbcr=8, irq_msk=1
 pxa27x-udc pxa27x-udc: ep0:set_ep0state:
state=WAIT_FOR_SETUP->SETUP_STAGE, udccsr0=0x2c1, udcbcr=8
 pxa27x-udc pxa27x-udc: ep0:handle_ep0_ctrl_req: SETUP 80.06 v0100
i0000 l0040
 pxa27x-udc pxa27x-udc: ep0:set_ep0state:
state=SETUP_STAGE->IN_DATA_STAGE, udccsr0=0x281, udcbcr=0
 pxa27x-udc pxa27x-udc: ep0:pxa_ep_queue: queue req
c393dbc0(first=yes), len 18 buf c386d000
 pxa27x-udc pxa27x-udc: ep0:write_ep0_fifo: in 16 bytes, 2 left,
req=c393dbc0, udccsr0=0x202
 pxa27x-udc pxa27x-udc: USB reset
 pxa27x-udc pxa27x-udc: USB reset start
 pxa27x-udc pxa27x-udc: ep0:req_done: complete req c393dbc0 stat -71
len 16/18
 g_ether gadget: setup complete --> -71, 16/18
 pxa27x-udc pxa27x-udc: ep0:set_ep0state:
state=IN_DATA_STAGE->WAIT_FOR_SETUP, udccsr0=0x200, udcbcr=0
 pxa27x-udc pxa27x-udc: ep0:handle_ep0: state=WAIT_FOR_SETUP,
req=(null), udccsr0=0x200, udcbcr=0, irq_msk=1
  r3:00000001 r2:20000013 r1:c3825f60 r0:c039601b
 [] (mount_block_root+0x0/0x2ac) from [] (mount_root+0x54/0x6c)
  r8:00000000 r7:00000013 r6:c0051e48 r5:00000000 r4:c039607f
 [] (mount_root+0x0/0x6c) from [] (prepare_namespace+0x12c/0x184)
  r5:c00203c1 r4:c00203ac
 [] (prepare_namespace+0x0/0x184) from [] (kernel_init+0x114/0x154)
  r5:c00083d4 r4:c0416e60
 [] (kernel_init+0x0/0x154) from [] (do_exit+0x0/0x5dc)
  r4:00000000 r3:00000000
....

last months i ported my system form ancient 2.6.18 kernel to my current
kernel (2.6.36-rc4), but i remember that with 2.6.18 the rootfs's
booting from SD did work; so i re-loaded 2.6.18 zImage, and in fact the
SD roots booting worked properly; then i investigated a bit and i have
found that also with 2.6.19 it worked, while with 2.6.20 it stopped
working (i didn't try between 2.6.20 and 2.6.36-rc4 but if it's helpful
i can do it).
The only way to solve my problem was to 'patch' the file
drivers/Makefile, moving the mmc.o object file upward; here is a sort of
'patch', but i regret in advance for some 'possible' (i had to write
'sure', but i like to be modest person....) syntax mistake, but i'm not
in habbit with patches...:

 --- a/drivers/Makefile
 +++ b/drivers/Makefile
 @@ -44,7 +44,8 @@
  obj-y                += macintosh/
  obj-$(CONFIG_IDE)        += ide/
  obj-$(CONFIG_SCSI)        += scsi/
  obj-$(CONFIG_ATA)        += ata/
  obj-$(CONFIG_MTD)        += mtd/
  obj-$(CONFIG_SPI)        += spi/
 +obj-$(CONFIG_MMC)        += mmc/
  obj-y                += net/
 @@ -92,9 +93,8 @@
  obj-y                += lguest/
  obj-$(CONFIG_CPU_FREQ)        += cpufreq/
  obj-$(CONFIG_CPU_IDLE)        += cpuidle/
 -obj-$(CONFIG_MMC)        += mmc/
  obj-$(CONFIG_MEMSTICK)        += memstick/
  obj-$(CONFIG_NEW_LEDS)        += leds/
  obj-$(CONFIG_INFINIBAND)    += infiniband/
  obj-$(CONFIG_SGI_SN)        += sn/
  obj-y                += firmware/

stated that it's not clear to me why when i don't try to boot the
rootfs directly from the SD, its driver comes up in the right way, and
the SD works, while when i try to boot the rootfs from the SD i cannot
get things to work (maybe the device is not up yet when the VFS
tryies to come up in fact in such a situation i cannot read any log
about mmc0 device!), i was wondering if this patch could be fair or
maybe (probably) i'm missing some potential side effects???
any hint will be appreciated!!!
thanks and bye

-

dylan cristiani

--
Fortunately I?ve been adhering to a pretty strict, uh, drug regimen to
keep my mind, you know, uh, limber...
---