collected: own shiny kernel on the tolino shine

posted by on 2013.06.23, under bootloader, collected, general, kernel, linux, programming
23:

The (patched) kernel used in the Tolino Shine was made available (by accident) a few weeks ago. I mirrored the archive here:

md5 size/mb file
90e78f2f7fdfffe460c85651cae431a3 109 kernel.tar.gz

Extract the archive, export the path to the toolchain (if not done yet) and compile the kernel:


>export PATH=$PATH:/home/devel/projects/tolino_shine/own_uboot/kobo/gcc-linaro-arm-linux-gnueabihf-4.8-2013.04-20130417_linux/bin/
>make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-

U-boot uses a little header in front of images (kernel, initrd, …) to store informations about the content (so it knows how to handle the image data). Normally you could compile the kernel directly as u-boot compatible image by using the make target uImage – but lets do that by hand to see how it works (we need that u-boot header thingy again when it comes down to the initrd – so it is not about wasting time, won’t hurt and is done with one line… :) ).

_note: The mkimage tool is located in the tools folder of the u-boot sources so we need to export that path.


>export PATH=$PATH:/home/devel/projects/tolino_shine/own_uboot/uboot-imx/tools/
>mkimage -A arm -O linux -T kernel -C none -a 0x70008000 -e 0x70008000 -n "Shine Kernel" -d zImage shine_kernel.uboot
Image Name:   Shine Kernel
Created:      Sun Jun 23 16:13:38 2013
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    3275528 Bytes = 3198.76 kB = 3.12 MB
Load Address: 70008000
Entry Point:  70800000

_note: I took the address parameters -a (load address) and -e (execute address) from the original u-boot.

From ntx_comm.c (#define SD_OFFSET_SECS_KERNEL 2048) and the boot log (MMC read: dev # 0, block # 2048, count 8192 partition # 0 ) we know that the boot-loader expects the kernel at 0×800*0×200 = 0×100000 on the SD card.

_note: the #define DEFAULT_LOAD_KERNEL_SZ 8192 sets the maximum for the kernel size (here 4MB)

So lets write our u-boot header equipped kernel to that position on the disk…


#>dd if=shine_kernel.uboot of=/dev/SDCARD seek=2048 bs=512

It boots… and crashes:


MMC read: dev # 0, block # 1, count 1 partition # 0 ... 
1 blocks read: OK
hwcfg rootfstype : 2
hwcfg partition type : 7
## Booting kernel from Legacy Image at 70800000 ...
   Image Name:   Shine Kernel
   Created:      2013-06-23  16:05:55 UTC
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    3275528 Bytes =  3.1 MB
   Load Address: 70008000
   Entry Point:  70008000
   Loading Kernel Image ... OK
OK
-
Starting kernel ...
-
Uncompressing Linux... done, booting the kernel.
Initializing cgroup subsys cpu
Linux version 2.6.35.3 (devel@bigplay) (gcc version 4.8.1 20130401 (prerelease) (crosstool-NG linaro-1.13.1-4.8-2013.04-20130417 - Linaro GCC 2013.04) ) #109 PREEMPT Sun Jun 23 00:15:35 CEST 2013
CPU: ARMv7 Processor [412fc085] revision 5 (ARMv7), cr=10c53c7
..................
mxc_epdc_fb_fw_handler-3619] 
drivers/video/mxc/mxc_epdc_fb.c(3654):EPD 1024x758 
Unable to handle kernel NULL pointer dereference at virtual address 00000026
pgd = 80004000
[00000026] *pgd=00000000
Internal error: Oops: 5 [#1] PREEMPT
last sysfs file: 
Modules linked in:
CPU: 0    Not tainted  (2.6.35.3 #109)
PC is at epdc_firmware_func+0x10c/0x2a4
LR is at epdc_firmware_func+0x68/0x2a4
................

The last regular output prints a file (drivers/video/mxc/mxc_epdc_fb.c) and a line number (3654). A few lines later (3694) some data is copied from waveform… remember the u-boot output @ boot:


...........
MMC read: dev # 0, block # 14335, count 1 partition # 0 ... 
1 blocks read: OK
no "waveform" bin header
...........

Yeah, it is missing- and the code will crash if it is not there. Learned: it seems the waveform contains the frame buffer configuration. Same procedure as every year: extract the waveform image from the SD card backup and put it on our new card… The header including the magic number starts at 0x6ffff0. The size is given at mem(magic number + 8) -> (AF 66 11 00). Interpreted as an unsigned long we got a size of 1140399 bytes (but we copy 1140431 := 1140399 + 32 byte header). The waveform data starts at 0×700000. Copy now!


>dd if=first_16_mb_sd_card.img of=waveform.img bs=1 skip=7340016 count=1140431
#>dd if=waveform.img of=/dev/SDCARD bs=1 seek=7340016 obs=512

md5 size/mb file
7d440e0d24b2ee89c280d83ecf55452d 1 waveform.img

Insert the card, cross the fingers – boot… works :). On boot the display is initialized – the screen turns black for two times. But now the kernel dies with:


VFS: Cannot open root device "mmcblk0p1" or unknown-block(179,1)
Please append a correct "root=" boot option; here are the available partitions:
b300         1966080 mmcblk0 driver: mmcblk
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,1)
[<8003d250>] (unwind_backtrace+0x0/0xe0) from [<8046c620>] (panic+0x68/0xd8)
[<8046c620>] (panic+0x68/0xd8) from [<80008e50>] (mount_block_root+0x1c0/0x200)
[<80008e50>] (mount_block_root+0x1c0/0x200) from [<800090c0>] (prepare_namespace+0x128/0x17c)
[<800090c0>] (prepare_namespace+0x128/0x17c) from [<80008aac>] (kernel_init+0x120/0x17c)
[<80008aac>] (kernel_init+0x120/0x17c) from [<80039954>] (kernel_thread_exit+0x0/0x8)

But that is okay and will be fixed in the next part. (Complete boot log including kernel: here)

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