RE: [Fastboot] [PATCH]IA64 kexec/kdump patch for INIT

Takao Indoh
2006-09-07T14:48:51Z

On Thu, 7 Sep 2006 21:01:17 +0800, "Yu, Luming" wrote:

>>>Did saved Os gp in SAL OS state somehow get overridden before
>>>ia64_set_kernel_registers prior to invocation of ia64_init_handler?
>>>
>>>I assume the following code (in ia64_set_kernel_registers )
>>should restore
>>>correct GP value.
>>>
>>>ia64_set_kernel_registers:
>>> ...
>>> ;;
>>> ld8 r1=[temp4] // OS GP from SAL OS state
>>
>>Yes, but this gp value is physical address.
>>In the next line, gp is changed to virtual address.
>>
>>DATA_PA_TO_VA(r1,temp1)
>>
>>This macro just sets region7 bit, so gp value becomes region7 address.
>
>Ok, could you please confirm what is the value of r1 before
>DATA_PA_TO_VA(r1, temp1)?
>I guess we need to set r1 = __gp in ia64_set_kernel_registers.
>If not, this is a bug. Am I right?

In the ia64_mca_init, the value of ia64_tpa(ia64_getreg(_IA64_REG_GP)
is registered as gp value. When cpu comes into the above code, r1 is set
to this value, I think. Therefore, r1 has physical address of __gp
before DATA_PA_TO_VA(r1, temp1). How do you think?

I think you are right, I also think r1 has to be set to __gp before
calling ia64_init_handler.

Regards,
Takao Indoh