Hi all,
BIOS issues identify device for PATA/SATA drives. Does it save this information somewhere? Is it possible to retrieve information about disk drives from BIOS rather than check if drive is present on the bus and then issue IDENTIFY DEVICE to each of them?
What I need is to get vendor information (model, etc.) for available hard disks.
Thanks in advance.

Int 0x13 Fn 0x25 - Identify Device.
DL = drive number (80h,81h)
ES:BX - 512 byte buffer for reply packet

but this function is optional... will try it if it works on my PCs when i arrive home, and also if it works for all drive numbers, not only 0x80 and 0x81

edit: seems like EDD-4 defines this function as mandatory

this function didn't work on all pcs i tried. moreover, function 48h doesn't return extended information (above offset 30 in the Resul Buffer as specified in EDD spec.). bios doesn't assign a number to optical drives unless user boots from cd in no-emulation mode... my verdict - bios sucks!

zhak: I think you are expecting too much from the BIOS. The 'B' really does mean what the letter stands for.

Once you have you boot code loaded and running the job of the BIOS is mostly done. From that point on your code is expected to find devices and things on its own.

@revolution: You got it right. In order to get the proper information one needs
to use low level methods.

Regards
Mac2004

I'm in the process of adding scanning for basic devices to my loader stage and found that BIOS', in general, will only return hard disks mapped to PATA ports.

I came across the EDD a while ago too and found that some BIOS' would only fill either the EDD or the xPath information - you can reconstruct one from the other in some cases.

If your OS is going to run 32/64bit protected mode, you might as well write as much of it yourself as possible for reuse.

It does but only for new PCs. DPTE was introduced in v2. You can get port numbers from it, scan PCI for IDE controllers and check BARs of both channels.