Re: network support : memory management problem

[Vincent Guffens]

it looks like the problem is gone. I changed the way I allocate the 
memory to hold a block. I changed from:

int load_block ()
        char * p = (char *) grub_malloc(len*sizeof(char));

to

int load_block ()
        char * p;
[...]
p = (char *) grub_malloc(len*sizeof(char));


but still, I would be interested in documentation about the memory 
layout and the memory management of grub2, if available.

Thanks !



Vincent Guffens wrote:
> Hi,
>
> I sent a similar e-mail yesterday but I think it didn't get through.
>
> I have a working version of the netboot support in grub2. I can issue 
> commands like (seeking in file is not yet possible):
>
> cat (nd0)test.txt
> linux (nd0)linux24
>
> but depending on where in the code I free my data blocks, I sometimes 
> get a  "free magic is broken" fatal error msg from grub_free().
>
> I found out that if I use the grub_printf() function just before the 
> call to grub_free(), the problem disappears.
>
> That is to say that in my grub_net_close function (the close file 
> function associated with the net binding file system), I do something like:
>
> struct grub_netfs_data * priv =  (struct grub_netfs_data *) file->data;
> struct grub_netfs_block *pp, * p = priv->head;
>
> grub_printf("FREEING\n");
>
> if (p)
>   pp = p->next;
>
>   while (p) {
>     if ((p->data)){
>       grub_free(p->data);
>     }
>
>
> If I remove the FREEING msg, I have the panic error message, otherwise, 
> everything looks fine. The exact error message is
>
> free magic is broken at 0x85900: 0x0
>
> Does someone has an idea ? Is there some documentation available about 
> the mm in grub2 ?
>
> The full code is available on this web page:
> http://www.auto.ucl.ac.be/~guffens/grub2_netboot/index.html


--
                                Vincent Guffens
                                PhD Student UCL/CESAME
                                tel:   +32 10 47 80 30
Value your freedom, or you will lose it, teaches history.
"Don't bother us with politics," respond those who don't want to learn.
                -- Richard M. Stallman