On Wed, 2005-06-08 at 21:47 -0700, Joel Vink wrote:
> A great feature of the current Macintosh ROM (firmware) which is
> based on Open Firmware (OF, http://playground.sun.com/1275/) is the
> ability for PCI adapter cards to include both the Open Firmware
> driver, if required for booting, and also the Mac OS driver
> "encapsulated" for the PCI adapter card. This allows the Macintosh
> platform to have the true "plug and play" elegance of a PCI adapter
> card appearing to be "driverless" because the user simply puts the
> card in the Macintosh and it "just works". The current Windows
> environment is vastly interior by requiring some type of BIOS driver
> to reside in the PCI adapter card ROM to boot, but then during boot,
> the Windows environment will "detect new hardware" and require a disk
> to be available to install the Windows OS driver.
What about PCI/AGP cards booting on both platforms ? There is a VERY
SIGNIFICANT advantage is staying with Open Firmware here: A video card
or SCSI card with an OF driver would be useable for booting on both
existing PPC machines and newer x86 machines.
Without that feature, it would require to have both firmwares on the
card, which, while possible, is a huge waste of flash space. Flash is
expensive and most cards only have a limited amount of it.
In general, Open Firmware is a great thing, though we could maybe blame
companies using it today (no name :) for not keeping the working group
alive and slowly letting their implementations drift away from the
standard without ever trying to keep the standard alive...
On a similar topic, IBM just released on open source "slim" open
firmware implementation (still early version, I think it still lacks
f-code support, pure forth only for now) which we intend to push to
embedded developpers as much as possible.
> If Intel's Extensible Firmware Interface (EFI, http://www.intel.com/
> technology/efi/index.htm) used as the ROM code for a Macintosh based
> on an Intel processor would still allow PCI adapter cards to include
> not only the pre-OS boot drivers, but also the actual Mac OS driver
> "encapsulated", then EFI would seem to provide as good as solution as
> the current OF. Otherwise it would seem that OF has very distinct
> "end user experience" advantage over EFI. Can anyone clarify if EFI
> would support PCI adapter cards with their own ROM's having both the
> pre-OS boot drivers and also the Mac OS driver "encapsulated" that
> would give the user experience of "driverless" PCI adapter cards?
I'm not too concerned by having the OS driver in the card's ROM. If the
firmware driver has enough to setup an early display (video), load the
kernel (block device), netboot (network device) etc... then the
bootloader (BootX) currently does a boot job of picking the OS driver on
the root partition and giving it to the kernel at boot. That still
requires installation of a driver when installing the card but I don't
think it's that bad.
I am more concerned by compatibility of card firmware with existing PPC
macs.
Ben.
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