trini at kernel.crashing.org
Thu Sep 16 09:48:28 EST 1999
On Wed, 15 Sep 1999, Ethan Benson wrote:
> On 15/9/99 Peter Bierman wrote:
> >The bootblock on a Macintosh is specified as a structure in an HFS filesystem.
> therein lies the problem....
That's not a problem, that's helpful. As Kevyn pointed out (maybe just on
IRC) is if you nuke the NVRAM on a SPARC, yer dead. If you do that on a
Mac, you're fine. Lots of other archs have the same problem. re-write
your bootblock, you're dead on x86. Macs have the "Can't shoot my foot
off" feature. This isn't bad.
> >So I'm not sure what you mean then by the "bootblock of the disk".
> on intel machines disks are typically use the very first 512 bytes on
> a disk as a bootblock and partition table, the bootblock portion of
> this is something like 446 bytes long, the BIOS when booting the
> machine has a boot device specified all it does it load that 446
> bytes into memory and execute it that code could be the NT loader the
> old DOS/win95 loader or it could be LILO, that code then can do
> whatever it need to do. in lilos case it loads its second stage
> loader from the root filesystem and that takes care of loading the
> kernel, if you replace ext2fs with xfs all that needs updating is
> possibly the second stage LILO. no specific partition or filesystem
> is needed and the BIOS does not care what filesystem you use.
But a good loader knows how to deal w/ FSes. The FreeBSD loader is
wonderful, and can boot any kernel on the disk, unlike lilo.
> > >requiring a dedicated partition for the BOOTSTRAP is ridiculous.
> > >and so is chaining oneself to a single filesystem (HFS)
> >NewWorld machines have flashable firmware, and OF can then be updated to
> >understand different filesystems.
> filesystem code does not belong in the firmware. its not needed
> either if the boot process is done like it is on intel machines,
> which works pretty darn well if you ask me.
> >But I still have to support the ability to boot *before* OF gets updated.
> >So for UFS systems on NewWorld machines, we have an HFS volume that
> >contains all of the OF patches we need, and the booter to find and launch
> >the kernel from the UFS volume.
> fine maybe you need this on older machines, but the newer machines
> should fix this deficiency, and sport a filesystem INDEPENDANT boot
> process, this way linux and BSD folks don't have to go though such a
> large pain to get their OSes to boot.
Why do you need a filesystem independant boot process? That limits us to
something tiny, rather useless and ugly.
> >HFS systems on NewWorld machines will just boot directly from the root volume.
> if the root volume is HFS, I don't want to use HFS, I like UFS just
> fine, and what if I add xfs or someother filesystem support to darwin
> how do it boot it now? I have to go back to this messy bootstrap
> partition junk.
Thats the price to pay for something nice and elegant.
> can you see why relying on HFS or any specific filesystem is inconvenient???
> if you cannot get around the partition hack on older machnes fine use
> it there, but for the newworld flashable macs and all future please
> make a filesystem agnostic boot process. that is really all I am
> asking of apple.
Why? Why would apple spend all sorts of time and money on something that
gains them nothing.
Tom Rini (TR1265)
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