lkml.org 
[lkml]   [2010]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: x86 embedded - Problem getting past 'move compressed kernel before decompression'
Graeme Russ wrote:
> H. Peter Anvin wrote:
>> On 03/01/2010 11:41 AM, Graeme Russ wrote:
>>> H. Peter Anvin wrote:
>>>> On 03/01/2010 03:56 AM, Graeme Russ wrote:
>>>>> I have done a little more digging. By adding an ascii string before
>>>>> relocated: label, I am able to determine that the int3 after the relocated:
>>>>> label exists in bzImage at offset 0x1C3FD7
>>>>>
>>>>> EAX holds (for the jump) 0x5379d0 (different bzImage of course). The
>>>>> contents of memory at this address is in bzImage at offset 0x1C09D7 - A
>>>>> difference of 0x3600 (seems too even to be random)
>>>>>

I've had a close look at the memory dumps and it looks like U-Boot is not
loading in the .text section which is _after_ the compressed vmlinux. This
is what contains the code after the relocated: label. Looks like the
bzImage anatomy information on the net is a little out of date - They
appear to have all the decompression code before the compressed kernel...

I've taken a slightly different tack now - I am tftp'ing the entire bzImage
to 0xfca00 (0x100000 - 0x3600) and adjusting the setup_header pointer to
0xfca00 + 0x1f1 and jumping to 0x10000. After a few false starts, I am able
to get an lzo compressed bzImage up to startup_32 in arch/x86/kernel/head_32.S

My next problem is at Enable Paging:

/*
* Enable paging
*/
movl $pa(swapper_pg_dir),%eax
movl %eax,%cr3 /* set the page table pointer.. */
movl %cr0,%eax
orl $X86_CR0_PG,%eax
movl %eax,%cr0 /* ..and set paging (PG) bit */
ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */


The kernel crashes at:
movl %eax,%cr0 /* ..and set paging (PG) bit */

Argh, so close, yet so far :(

regards.

Graeme


\
 
 \ /
  Last update: 2010-03-05 14:05    [W:0.052 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site