[syslinux] Bugs in pxelinux.asm - syslinux 3.75

[H. Peter Anvin]

pfranz73 at tiscali.it wrote:
> In pxelinux.asm
> the xchg instruction in
> 
>                 xchg ax,ax
> .
> data_on_top:
> 
> should be xchg ax,dx, I think
> At the end of 
> pxe_get_cached_info routine,there is
>                 and ax,ax
> 
>                 jnz .err
> It is supposed to test for AX status, but 
> since pxenv does pushad and popad, AX doesn't contain status. In fact 
> the other routines calling pxenv don't have this bug.
> pxe_unload seems 
> to be never called; if so, also RealBaseMem is unused.
> According to the 
> specification, pxe_unload_stack_pkt.reserved are 10 bytes, not 10 words
> 

unload_pxe is called via the UNLOAD_PREP macro as well as from comboot.inc.

The other issues are valid, of course.

	-hpa