2.6.18 fails in call_usermodedata() on 8xx

2.6.18 fails in call_usermodedata() on 8xx

[Robin Gilks]

Greetings

Having (sort of) mastered the bdi2000, I'm trying to bring up a 8xx card
thats been debugged and working with a 2.4 kernel for the last 3 years
but is failing miserably on a 2.6.18 kernel.

My initial problems in dma_alloc_init I seem to have fixed by moving
CONFIG_CONSISTENT_START to 0xa0000000 from the default of 0xff100000 but
now I'm failing in call_usermodedata(). Any attempt to check the values 
of structures (eg. current->fs->root) results in an error of the form:

(gdb) print *current
Cannot access memory at address 0xc01e27a8

so I'm a bit stuck with further debugging.

Is there anything I should be looking out for in particular with an 8xx
CPU and a late 2.6 kernel? My understanding was that it now worked but
the config documentation is a bit thin on the ground :-(

Cheers

-- 
Robin


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Re: 2.6.18 fails in call_usermodedata() on 8xx

[Robin Gilks]

Robin Gilks wrote:
> Greetings
> 
> Having (sort of) mastered the bdi2000, I'm trying to bring up a 8xx card
> thats been debugged and working with a 2.4 kernel for the last 3 years
> but is failing miserably on a 2.6.18 kernel.
> 
> My initial problems in dma_alloc_init I seem to have fixed by moving
> CONFIG_CONSISTENT_START to 0xa0000000 from the default of 0xff100000 but
> now I'm failing in call_usermodedata(). Any attempt to check the values 
> of structures (eg. current->fs->root) results in an error of the form:
> 
> (gdb) print *current
> Cannot access memory at address 0xc01e27a8
> 
> so I'm a bit stuck with further debugging.
> 
> Is there anything I should be looking out for in particular with an 8xx
> CPU and a late 2.6 kernel? My understanding was that it now worked but
> the config documentation is a bit thin on the ground :-(
> 
> Cheers

Never mind - was the watchdog going off - now disabled in the bootloader 
so I'm getting much further than i thought...

Just the console & rootfs to get going now :-)

-- 
Robin



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This email, including any attachments, is only for the intended
addressee.  It is subject to copyright, is confidential and may be
the subject of legal or other privilege, none of which is waived or
lost by reason of this transmission.
If the receiver is not the intended addressee, please accept our
apologies, notify us by return, delete all copies and perform no
other act on the email.
Unfortunately, we cannot warrant that the email has not been
 altered or corrupted during transmission.
=======================================================================

Re: 2.6.18 fails in call_usermodedata() on 8xx

[Jim Heck]

Robin,

Could you provide some more details of your problem with dma_alloc_init 
for the 8xx.  I posted a few days back on Saturday about problems I was 
having getting an RPXLiteDW (based on the 823) to work with a late 
2.6.xx kernel.  I had traced the problem down (working without a probe) 
to problems with cpm_dpalloc() and cpm_dpram_addr() in the allocation of 
DP Ram buffers for the network loopback device.  DMA rings a bell since 
the failure occurred near where the /arch/ppc/8xx_io/enet.c driver is 
calling  dma_alloc_coherent().

The details on what code you had to change in the kernel, and the 
problems you were seeing might help me greatly.

Thanks for any help,

-Jim Heck

Robin Gilks wrote:
> Greetings
>
> Having (sort of) mastered the bdi2000, I'm trying to bring up a 8xx card
> thats been debugged and working with a 2.4 kernel for the last 3 years
> but is failing miserably on a 2.6.18 kernel.
>
> My initial problems in dma_alloc_init I seem to have fixed by moving
> CONFIG_CONSISTENT_START to 0xa0000000 from the default of 0xff100000 but
> now I'm failing in call_usermodedata(). Any attempt to check the values 
> of structures (eg. current->fs->root) results in an error of the form:
>
> (gdb) print *current
> Cannot access memory at address 0xc01e27a8
>
> so I'm a bit stuck with further debugging.
>
> Is there anything I should be looking out for in particular with an 8xx
> CPU and a late 2.6 kernel? My understanding was that it now worked but
> the config documentation is a bit thin on the ground :-(
>
> Cheers
>
>