boot methods

[Paul Mackerras]

Michael Sokolov writes:

> But currently the vmlinux boot interface is defined per platform: the generic
> code passes the initial R3-R7 to platform_init(). It should be possible for a
> board port maintainer to change this interface in his/her port without
> affecting anyone else.

Yes, that is a very good point.

> In arch/ppc/kernel/setup.c
> change the division of labor between machine_init and parse_bootinfo. Move the
> current logic for locating bi_recs in memory from parse_bootinfo to
> machine_init, passing the pointer to bi_recs to parse_bootinfo() as an
> argument. Then new board ports can be designed with a bi_recs interface instead
> of the current traditional one by doing something like parse_bootinfo(r3) in
> platform_init.

An excellent suggestion.  Thank you.  Is anyone using the bi_recs in
anger yet?

For CONFIG_ALL_PPC, we need to make a wrapper which can be booted
using existing installed versions of BootX/quik/yaboot, which will
accept the parameters as provided by those loaders and make up a set
of bi_recs.  Then we can require that pmac/prep/chrp _always_ use a
wrapper, and then start to move the Open Firmware calls into the
wrapper.

Other platform maintainers can use a wrapper or not as they choose.
For consistency and simplicity it would be nice if there was a
standard register assignment on entry, for example having the physical
address of the bi_recs in r3, but that is not essential.

We should all agree on a comment set of bi_rec tags and the format for
each type of entry.  And I like Ben's suggestion of keeping the bi_recs
around.

Reactions?  Thoughts?  Comments?

Paul.

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