Re: miBoot 1.0d3

Re: miBoot 1.0d3

[Benjamin Herrenschmidt]

On Mon, Sep 20, 1999, Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
wrote:

>That would indeed be nice. FYI, Amiga-Lilo can boot AmigaOS, since we
>disasembled the ca. 20 bytes of code in the boot block.

With the current miBoot mecanism, we must either manage to have MacOS ROM
try another disk, or change the way miBoot works. The current scheme
initializes the file system and opens the fake System file. Changing to a
real MacOS System file on the fly would be very complex and dangerous. We
need the ROM to be able to close it and re-open a new boot volume.

Another solution would be to stuff miBoot in the bootblocs (a kind of
primary loader, which will itself load the remaning code _before_ the
file system is initialised. The initialisation is done in the bootblock
code). That means having some kind of "map" of the physical location of
the real boot file. I know how to build this map from MacOS but the trick
I use for this is not compatible with BlueBox (this may not be a problem
after all). I don't know if it's possible under Linux but I beleive it is.

Also, I could load this secondary bootstrap using direct SCSI or ATA
calls, but this may be difficult to fit in the bootblocks. The simplest
solution is to have them on the same HFS partition as the real System
file. This way, I can use simple PBReadSync from the root volume's driver.

More hacking next week end unless I find some spare time this week
(unprobable).


-- 
           Perso. e-mail: <mailto:bh40@calva.net>
           Work   e-mail: <mailto:benh@mipsys.com>
BenH.      Web   : <http://calvaweb.calvacom.fr/bh40/>


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miBoot 1.0d3

[Benjamin Herrenschmidt]

HI !

miBoot 1.0d3 is online at http://calvaweb.calvacom.fr/bh40/test.html

I booted successfully Paul's latest 2.2.12 with a normal xcoff zImage, it
should also work with plain images (vmlinux, usually too large for a
floppy), zImage with initrd, and plain vmlinux compressed with -vf9
option. I didn't test zImage with initrd. (Note that the image is
decompressed by miBoot, the decompression "header" is bypassed.

The kernel file name is currently stored in resource STR# 128.

next on my list:

 - get rid of the Apple boot blocs (write my own). Note that in theory,
using the 68k bootblocs, it may be possible to boot from an ext2
partition (using a first stage loader with a "map" like we do with OF)

 - add some kind of gui to choose the root volume, options, and to be
able to change the video resolution when using video=ofonly (by calling
the ROM video driver).

Another issue is that I have currently no way to exit from miBoot. If I
fail to boot Linux, I exit to the caller, the disk is ejected, but the
machine doesn't try another disk to boot from. It may ne possible, it may
not, I'll have to disassemble more of MacOS ROM in order to figure this
out. I'd like to have a choice to boot MacOS, especially when miBoot is
on a hard disk partition.  (I can still change the PRAM value and reboot).



-- 
           E-Mail: <mailto:bh40@calva.net>
BenH.      Web   : <http://calvaweb.calvacom.fr/bh40/>


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Re: miBoot 1.0d3

[Geert Uytterhoeven]

On Sun, 19 Sep 1999, Benjamin Herrenschmidt wrote:
> Another issue is that I have currently no way to exit from miBoot. If I
> fail to boot Linux, I exit to the caller, the disk is ejected, but the
> machine doesn't try another disk to boot from. It may ne possible, it may
> not, I'll have to disassemble more of MacOS ROM in order to figure this
> out. I'd like to have a choice to boot MacOS, especially when miBoot is
> on a hard disk partition.  (I can still change the PRAM value and reboot).

That would indeed be nice. FYI, Amiga-Lilo can boot AmigaOS, since we
disasembled the ca. 20 bytes of code in the boot block.

Greetings,

			Geert (who actually doesn't care about  MacOS at all)

--
Geert Uytterhoeven ----------------- Sony Suprastructure Center Europe (SUPC-E)
Geert.Uytterhoeven@sonycom.com ------------------- Sint Stevens Woluwestraat 55
Phone +32-2-7248608 Fax +32-2-7262686 ---------------- B-1130 Brussels, Belgium


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