Custom ramdisk

Adam Lackorzynski adam at
Tue Apr 1 00:00:47 CEST 2014


On Mon Mar 31, 2014 at 20:07:34 +0400, Tim Komarov wrote:
> I use Pandaboard for my practising with Fiasco.OC and L4Linux.
> 1) I got a problem with booting L4Linux with my own ramdisk. When I use 18 mb ramdisk, I got the following error:
> reading image.elf šššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššš
> 24691072 bytes read šššššššššššššššššššššššššššššššššššššššššššššššššššššššššššš
> ## Starting application at 0x81000000 ...
> ...
> ,,,[Everything is usual]
> ,,,
> NET: Registered protocol family 17                                                       
> List of all partitions:                                                                  
> No filesystem could mount root, tried:  ext3 ext2 ext4 cramfs                            
> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)           
> CPU: 0 PID: 1 Comm: swapper Not tainted 3.13.0-l4 #1                                     
> [<0200c624>] (unwind_backtrace+0x0/0xec) from [<020054c0>] (show_stack+0x10/0x14)        
> [<020054c0>] (show_stack+0x10/0x14) from [<0222e63c>] (panic+0x7c/0x1b8)                 
> [<0222e63c>] (panic+0x7c/0x1b8) from [<022f2c40>] (mount_block_root+0x25c/0x29c)         
> [<022f2c40>] (mount_block_root+0x25c/0x29c) from [<022f2f44>] (prepare_namespace+0x160/0)
> [<022f2f44>] (prepare_namespace+0x160/0x1b4) from [<022f2894>] (kernel_init_freeable+0x1)
> [<022f2894>] (kernel_init_freeable+0x174/0x1b8) from [<0222ccf0>] (kernel_init+0x8/0x118)
> [<0222ccf0>] (kernel_init+0x8/0x118) from [<020077d4>] (ret_from_fork+0x14/0x20)         
> [<020077d4>] (ret_from_fork+0x14/0x20) from [<00000000>] (  (null))                      
> panic: going to sleep forever, bye         
> To make ramdisk I simply create a file, write 18 Mb of zeroes to it
> (with dd), create in that file ext2 partition and copy there files
> from ramdisk-arm.rd
> So, what should I do to get a proper working ramdisk?

Hmm, is the expected ramdisk size big enough? I.e. a ramdisk_size=18500
on the cmdline could help here. (On the other side the according error
message is missing, so maybe not.)

> 2) Even more. If I create 20 mb ramdisk, I got this:
> reading image.elf ššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššš
> 26788224 bytes read ššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššššš
> ## Starting application at 0x00000000 ... š
> Than the booting hangs. Why so? 

Just guessing, loading the ramdisk has overwritten u-boot? So you could
try changing the load address in u-boot a bit and see if it changes something?
bootstrap will start from anywhere, so you can use the same binary.

Adam                 adam at

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