[OpenBIOS] Probing the PCI bus for Option ROMs.

[Joe van Tunen]

On 4/3/18, 1:17 PM, "Mark Cave-Ayland" <mark.cave-ayland at ilande.co.uk> wrote:

    On 02/04/18 21:51, Jd Lyons wrote:
    
    > Joe, if it would be something that interests you, and you have the time, 
    > we could work on adding proper PCI Probing to Openbios.
    > 
    > As it stands the Qemu_VGA is a pci device, and Qemu loads an Option rom, 
    > but it’s the VGA Bios and Opennbios doesn’t probe for option roms. 
    >   Openbios has the Fcode for the Qemu-Vga device and there is a NDRV 
    > that gets loaded from a file.
    > 
    > What we really need is to make a proper FCode Rom image with the NDRV 
    > for the Qemu_VGA device, we could make a hybrid Bios/Fcode rom and not 
    > have to change the code in Qemu at all, I don’t think.
    > 
    > Here are some instructions on setting up and building Openbios on OS X 
    > Intel.
    > 
    > There is an effective tutorial on the openbios site. If you run OSX, you 
    > nee to install the fcode utils and use the awos cross compiler linked 
    > to: http://www.mediafire.com/download/wy5xg ... pilers.zip 
    > <http://www.mediafire.com/download/wy5xgj2hwjp8k4k/AWOS_Cross-Compilers.zip>
    > 
    > This is my script to build the OpenBIOS binary:
    > PATH=:/usr/local/ppcelf/ppcelf/bin:/users/hsp/src/fcode-utils-devel/toke:$PATH
    > export PATH
    > cd openbios
    > CROSS_COMPILE=ppc-elf- ./config/scripts/switch-arch ppc
    > #(remove -Werror from CFLAGS in Makefile.target in top directory)
    > make
    > 
    > Best,
    > Cat_7
    > 
    > I forget the file that has the Forth for the Qemu_VGA device, Mark?
    
    You can find the QEMU VGA driver in drivers/vga.fs.
    
    Note that the NDRV is deliberately served from QEMU via the hypervisor 
    fw_cfg interface so that it is possible for QEMU to serve just the FCode 
    option ROM by default, rather than having to embed the full Mac driver.
    
    Getting OpenBIOS/QEMU to read a proper FCode ROM goes something like this:
    
    1) Get OpenBIOS's compiled QEMU,VGA.bin FCode image added to QEMU
    
    2) For certain machines (PPC/SPARC64) in QEMU replace the default PC 
    option ROM with the FCode Option ROM
    
    3) Hack vga_config_cb() to map the option ROM via the BAR (6) instead of 
    directly executing the embedded FCode binary via byte-load
    
    
    ATB,
    
    Mark.


Why not have a single Option ROM with both a BIOS and Open Firmware image? The BIOS or Open Firmware should be smart enough to loop through the images and select the correct one. Since the option roms are on disk, we don't have to limit the total size. I suppose there's little point because the same machine isn't used for both BIOS and Open Firmware?