Messages in this thread | | | From | "Peter 'Luna' Runestig" <> | Subject | Re: "Silly" question: Use "BIOS INT 0x13" call from user space? | Date | Thu, 23 Sep 1999 09:07:01 +0200 |
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From: Alan Cox
> > Is it possible to use the PC BIOS INT 0x13 call from user space? The aim is > > to figure out from which device an "El Torito" cd-rom booted. Or maybe that > > interface is totally gone when linux has booted? > > It is too late by then - you can call it from setup.S though and store the > value somewhere the kernel can get it back
Thanx for the hint. I started working with the idea to make the El Torito boot device available through "/proc/eltorito_bios" and in not to long, I had a patch ready that "should" work. But then I realized the real world of tech specs... I have tried several different PC's with BIOS'es from five different vendors (Compaq, AMI, Phoenix, Award and Adaptec (SCSI)), and I have yet to find a BIOS that confirms to the El Torito spec! By calling BIOS INT 0x13 func 0x4B, you can get info about IDE or SCSI, controler idx and device specification (master/slave or SCSI PUN/LUN) about the cdrom unit that booted us up. Only one (Award) sets the proper IDE/SCSI flags, on all the others you don't know even that! Some BIOS'es starts enumerate the controlers on 0, some on 1... Phoenix (you should think _they_ get it right since they host the spec) even return one byte more data than specified, dangerous! It seems hard to make something usefull out of this, but I haven't given up yet.
Cheers, Peter
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