Re: SCSI cdrom boot problem

[Tobias Diedrich <ranma@example.com>]

SN_Diamond wrote:
> > Booting first on SCSI usually means the integrated SCSI BIOS (Many BIOSes have
> > an integrated SCSI BIOS for the sym53c8xx or some chip like that IIRC).
> > I wouldn't expect that to change anything if it's an external SCSI card.
> 
> I thought booting first on SCSI meant handing boot control over to the SCSI
> BIOS that is found on the SCSI card (if such is installed).  After all, the
> motherboard's BIOS already handed control over to the SCSI BIOS on the SCSI
> card (if such is installed) for SCSI device enumeration.

No and yes.
On boot, the BIOS scans for adapter ROMS in the C000-FFFF address space.
If it finds a ROM it will execute this ROMS initialization function.
After that it continues the ROM-Scan until all ROMs are found and then
boots the system.

If you have an SCSI card with its own SCSI-BIOS, this will be detected and
initialized by the BIOS. The initialization function of the SCSI-BIOS does
the device scan, hooks some interrupt vectors (Int 0x13 and Int 0x19) and
returns control to the BIOS.

If the BIOS decides it is time to load the boot sector it will do an Int 0x19,
which does the loading stuff. At that time the SCSI-BIOS will get control again
(if it has hooked this interrupt) and can do things like booting from cd.

This all is not dependend on the BIOS "Boot from SCSI/IDE" settings, which 
control BIOS internal boot behaviour. BIOSes which have the SCSI setting available do have a built-in SCSI ROM for some SCSI-chipset, which will be loaded if this chipset is detected.

-- 
Tobias
nya~ni ?