Re: Memory image save/restore

[Chris Lalancette <chris.lalancette@gd-ais.com>]

Paulo,
    Thanks for responding.  You are right in that the state of memory 
isn't the state of the entire machine; however, for instance, the 
swsusp2 project can save the contents of memory out to disk, go to 
sleep, and then resume to it later.  Basically, what I am trying to do 
is something like swsusp2, with less restrictions; I know I have another 
region the size of physical memory to work with, I know I am executing 
from an interrupt handler, and at the end I don't want to go to sleep, 
just continue on.  Then I might want to use that memory image later.

Thanks,
Chris Lalancette

pmarques@grupopie.com wrote:

> Chris Lalancette wrote:
>
>> Hello all,
>>
>>    I have been trying to implement some sort of save/restore kernel 
>> memory image for the linux kernel (x86 only right now), without much 
>> success.  Let me explain the situation:
>>
>> I have a hardware device that I can generate interrupts with.  I also 
>> have a machine with 512M of memory, and I am passing the kernel the 
>> command line mem=256M.  My idea is to generate an interrupt with the 
>> hardware device, and then inside of the interrupt handler make a copy 
>> of the entire contents of RAM into the unused upper 256M of memory; 
>> later on, with another interrupt, I would like to restore that 
>> previously saved memory image.  This way we can go "back in time", 
>> similar to what software suspend is doing, but without as many 
>> constraints (i.e. we have a hardware interrupt to work with, we 
>> reserved the same amount of physical memory to use, etc.).  Before I 
>> went much further, I figured I would ask if anyone on the list has 
>> tried this, and if there are any reasons why this is not possible.
>
>
> You're assuming that the state of the memory is the *state* of the 
> entire system.
>
> This fails because there is a lot of state information in hardware 
> registers, external peripheral devices, etc., etc.
>