BDI2000 PTEs

Hi, all

I am trying to do module debugging. Module is loaded atvirtual address
0xC500004C. At the moment I have memory translation enabled in BDI2000.
PTBASE is set to 0xf0 and this entry is cleared. This works for kernel
debugging, but memory translation fails when I try to do dynamically loaded
module debugging.
I guess I have to set PTE pointers for BDI2000.

First I put value 0xC00000F4 into physical address 0xF0 (BDI2000 PTBASE).

From Linux Jernel Book, I understood that PTE pointer is at variable called

"swapper_pg_dir". I tried to write its address into BDI2000 PTE kernel
pointer (physical address 0xF4).

Does not work.
I think that PTEs have to updated dynamically, but I have no ideas where to
get them from.

Can anyone explain how to get the values for the PTE kernel and user
pointers?

I am using kernel 2.4.4. I looked at the later kernels that have BDI2000
support. Unfortunately, support is only 8xx CPUs, not 8260. (I looked into
files /arch/ppc/head.S. and /arch/ppc/head_8xx.S). It is difficult for me to
update corresponding 8260 code mainly because I am not sure what this code
does and I am not very familiar with PPC assembly.

Any help is appreciated,
Thanks.

Rudolf


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Rudolf Ladyzhenskii wrote:

..... At the moment I have memory translation enabled in BDI2000.
PTBASE is set to 0xf0 and this entry is cleared.

That's not correct.

.... This works for kernel
debugging, but memory translation fails when I try to do dynamically loaded
module debugging.

That's because without a page table the BDI2000 defaults to 1:1 translation.
By clearing the location above you told the BDI2000 that no page tables
are available.

I guess I have to set PTE pointers for BDI2000.

No, you don't.  Just use a newer kernel that has this feature available for
all processors.  You could also copy the couple of lines of code from a
newer kernel into your 2.4.4 if you insist.

Thanks.


	-- Dan


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