[syslinux] Re: Does pxelinux work with >1GB RAM?

H. J. Lu hjl at lucon.org
Mon Oct 7 15:36:25 PDT 2002


On Mon, Oct 07, 2002 at 03:20:49PM -0700, H. J. Lu wrote:
> On Mon, Oct 07, 2002 at 02:19:21PM -0700, H. Peter Anvin wrote:
> > H. J. Lu wrote:
> > > On Mon, Oct 07, 2002 at 12:18:39PM -0700, H. Peter Anvin wrote:
> > > 
> > >>>I looked at Intel PXE. It did something strange with stack before
> > >>>calling the main PXE function.
> > >>>
> > >>
> > >>I'm sure it does, but that's not horrendously specific.
> > > 
> > > 
> > > When Intel PXE client calls the PXE function, it switches stack to
> > > SS:SP = 0:0x7C00 and switches back afterwards.
> > > 
> > 
> > How wonderfully original.  It might be worthwhile to use a low stack in
> > PXELINUX just like SYSLINUX and ISOLINUX uses.  I'll try to release a
> > test version to see if that works.
> > 
> 
> I am not sure if the stack usage is really an issue. Intel PXE doesn't
> use any memory below 3MB. However, pxelinux uses memory between 0x1000
> and 0x7c00 for various buffers. According to PXE 2.1 spec, memory
> between 0x500 and 0x7c00 are reserved. I don't know if it makes a 
> difference.
> 

I moved most of buffers after the .text section. Now pxelinux works. I
think it is a bad idea to use memory between 0x1000 and 0x7c00 for
buffers since they are reserved. I will see if clearing them first
makes a difference.


H.J.



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