🚀 go-pugleaf

"karim bernardet" <bernardet.karim@wanadoo.fr> writes:

> Hello,
> 
> I m trying to code a program to do checkpointing (for a simple loop) on
> a Linux Intel box (just to understand how it works). To do that, I (try
> to) follow what is said for the condor's checkpointing
> (www.cc.gatech.edu/classes/cs6761_98_spring/condor.ps).
> So I save the data and the stack space (in 2 different files data.dat
> and stack.dat).
> The data space is from _etext to sbrk(0) (data+bss) and the stack space
> from
> STACKBOTTOM (which is well defined) to the stack pointer. I save the
> stack context too.
> The checkpointing is done when the program receive the SIGTSTP signal
> and I restart it with the flag 1.
> But I can t read the data segment when I restart the code :
> 
> $ ./a.out 1
> Recover ...
> Restoring Data Section
> data start=134516798
> data size=12226
> HEAP END=134529024
> Problem to read data segment nb=-1
> read: Bad address
> 
> Below I put my code.
> Thanks a lot if someone can help me


>       data_start=(long)&_etext;

I may be wrong,  but I believe the 'text' is the  code of the program,
not the data.  Memory for the code of the program is usually read-only
(because self modifying programs are bad and because it allows sharing
the program text between several processes, not to speak of the shared
libraries).

What about  &__data_start or &data_start?  (you'd need to  rename your
local variable).

-- 
__Pascal_Bourguignon__                   http://www.informatimago.com/
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