[syslinux] Problem with opening a file

[Marc Haisenko]

On Wednesday 11 February 2004 13:18, H. Peter Anvin wrote:
> Marc Haisenko wrote:
> > Hi folks,
> > I've got a problem with COMBoot (16 bit) in SYSLINUX 2.06: while the
> > write string call (ax=2, int 22h) works just fine, the open file call
> > (ax=6, int 22h) does nothing at all. Calling that function doesn't modify
> > any register, and doesn't modify the carry flag.
>
> Get 2.08, or better yet, 2.09-pre11.
>
> 	-hpa

Tried both, with the same result... I've included the source code of a little 
test program (uses the GNU assembler and linker, as and ld).

open.S is main test source, tools.S holds the print_registers routine which 
does what the name suggests ;-)

open.S tries to open itself via ax=6, int 22h... it prints the registers just 
before the int call and directly afterwards. If the call would succeed some 
registers would get changed and the carry flag would get cleared. If the call 
would fail, the carry flag would be set (uneven value for flags).

Neither happens, which is quite strange, IMHO. I already tried setting the 
carry flag to see whether it gets cleared, but no, it stays the same.

I called open.com by using a syslinux.cfg like this:

DEFAULT menu
LABEL menu
KERNEL menu.com

It would be nice if someone could confirm this behaviour (seen in VMWare 4.0) 
and where I should dig around to debug this problem.

Thanks a lot,
	Marc


-- 
Marc Haisenko
Linux Solutions
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