Alpha - how to fill the PC

Alpha - how to fill the PC

[Aneesh Kumar K.V]

Hi, 

 	I am trying to do  process migration between nodes  using alpha
architecture. For explaining what is happening I will take the process
getting migrated from node1 to node2. I am using struct pt_regs  for
rebuilding the process on  node2.I am getting the same  value of struct
pt_regs on node1 and on node2 ( I print is using dik_show_regs) Now I
want to set the value of registers including the program counter with
the value i got from node1. Right now I am doing
ret_from_sys_call(&regs). But then i am getting a Oops . The Oops
message contain all the register values same as that I got from node1
except pc and ra 

	Any idea where I went wrong ? 

 -aneesh 

Re: Alpha - how to fill the PC

[Tyler BIRD]

One thing I thought of is the process on lets say node2 have exactly the same
address space as on node 1 when it is migrated.  You could be trying to return from a syscall
to an address space of a process that doesn't exist on the node or hasn't migrated yet.

Just a thought

>>> "Aneesh Kumar K.V" <aneesh.kumar@digital.com> 12/16/01 06:19AM >>>
Hi, 

 	I am trying to do  process migration between nodes  using alpha
architecture. For explaining what is happening I will take the process
getting migrated from node1 to node2. I am using struct pt_regs  for
rebuilding the process on  node2.I am getting the same  value of struct
pt_regs on node1 and on node2 ( I print is using dik_show_regs) Now I
want to set the value of registers including the program counter with
the value i got from node1. Right now I am doing
ret_from_sys_call(&regs). But then i am getting a Oops . The Oops
message contain all the register values same as that I got from node1
except pc and ra 

	Any idea where I went wrong ? 

 -aneesh 



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Re: Alpha - how to fill the PC

[Aneesh Kumar K.V]

Hi,

No, I have the full address space rebuilt on node2. I validated it
checking /proc/<pid>/maps 

-aneesh  

 


On Mon, 2001-12-17 at 01:17, Tyler BIRD wrote:
> One thing I thought of is the process on lets say node2 have exactly the same
> address space as on node 1 when it is migrated.  You could be trying to return from a syscall
> to an address space of a process that doesn't exist on the node or hasn't migrated yet.
> 
> Just a thought
> 
> >>> "Aneesh Kumar K.V" <aneesh.kumar@digital.com> 12/16/01 06:19AM >>>
> Hi, 
> 
>  	I am trying to do  process migration between nodes  using alpha
> architecture. For explaining what is happening I will take the process
> getting migrated from node1 to node2. I am using struct pt_regs  for
> rebuilding the process on  node2.I am getting the same  value of struct
> pt_regs on node1 and on node2 ( I print is using dik_show_regs) Now I
> want to set the value of registers including the program counter with
> the value i got from node1. Right now I am doing
> ret_from_sys_call(&regs). But then i am getting a Oops . The Oops
> message contain all the register values same as that I got from node1
> except pc and ra 
> 
> 	Any idea where I went wrong ? 
> 
>  -aneesh 
> 
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org 
> More majordomo info at  http://vger.kernel.org/majordomo-info.html 
> Please read the FAQ at  http://www.tux.org/lkml/

Re: Alpha - how to fill the PC

[Richard Henderson]

On Sun, Dec 16, 2001 at 06:49:56PM +0530, Aneesh Kumar K.V wrote:
> Right now I am doing ret_from_sys_call(&regs).

Err, ret_from_sys_call is not a function that can be called in
any normal method.  Supposing that you get there, the stack 
must be set up properly, and the stack is whence the register
values are fetched.


r~