problems with stack sizes

Hi!

Like I said a long time ago, I've been trying to add support for signature
verification to etherboot for quite a while now. I've chosen to do so by
using libtomcrypt, which seemed quite compact and suited for this. I chose
to use sha1 with rsa signatures for this, this was chosen mainly to be
compatible with current stable openssl.

Well, I thought I was going on the good way till I got to face the problem
that the mpi library that tom uses on libtomcrypt needs memory management
functions (malloc, free, and realloc like functions), so chose to rewrite
that so that these functions were not needed (by allocating the needed space
in the variable definitions), and when I started to test that, I saw that
the stack that etherboot has is not big enough to hold all the big numbers
and calls to the functions.

For what I have read on the development doc, there is not much space to be
used, the stack grows towards the etherboot code and thus will overwrite it.
But I also read this: "This gives us about 1 MB for code, data, and stack.".
So I'm wondering if we have 1 meg... can't I make the stack bigger, if so,
what do I have to change?

I have played with the 4096 space for _stack on start32.S which I supposed
was the right place, but didn't quite look like it, any pointers?

If I cannot change the stack size or it is not recomended, can I reserve
some memory for data so that I could somehow manage that space?

Maybe I should forget about all that I have done till now with libtomcrypt
and start searching for lighter code that doesn't need this kind of stuff, I
saw the old sboot stuff, but the problem with that is that the rsa code it
uses is not free, any comments on this?

Well, as I'm new to etherboot I may be saying a lot of silly things, please
correct me whenever it's the case.

Thanks in advance!

Regards...
-- 
Manty/BestiaTester -> http://manty.net


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