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Re: RISC OS port

From: Timothy Baldwin
Subject: Re: RISC OS port
Date: Fri, 26 Nov 2004 00:47:45 +0000
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On Tuesday 23 Nov 2004 18:03, Marco Gerards wrote:
> Timothy Baldwin <address@hidden> writes:
> > During the past few months I have been working on a port to RISC OS an
> > ARM processors. It has reached the point where it can boot Linux, and IMO
> > is nearly ready to be included in CVS. It does not support to booting of
> > compressed Linux kernels as the decompression code has not been updated
> > to the new parameter passing convention.
> That is really nice!  Can you get the GRUB menu to work, etc?

I can't get menu to work on PC, grub-emu (which crashes), or RISC OS. I've 
tried with clean CVS source.

> How about module loading?  I noticed you wrote some code for that
> too...

Works. Not yet tested on processors with separate instruction and data caches, 
as I don't have any.

> I noticed you used a lot of assembler.  Isn't it possible to minimize
> the use of assembler somehow?  If that is not possible, no problem.

I've rewritten the RISC OS filesystem access code to use the C library, and 
I've rewritten some of the console code in C.

> > It includes support to access filesystems though the RISC OS filesystem
> > API, which error numbers should be returned in case of an error?
> I remember a discussion about this...  I noticed you implemented some
> disk access code.  Is it possible to access GNU/Linux partitions?

Not on the standard IDE interface, on a disc shared with RISC OS, because a 
partition module has yet to be written. 

> Is it possible to write support for the filesystem used on RISC OS?  I
> can help you with that, if you want that.

Attempting to use a filesystem handler within Grub would be unreliable due the 
filesystem also being mounted read/write.

> > The other ends which need tidying up before inclusion in CVS are:
> > Write a changelog
> > Fix copyright notices

Still to do.

> > Write support for ARMv4 (eg. StrongARM) and ARMv5 processors (eg.
> > XScale). Fix the arrow keys

Done. And ARMv6 processors hopefully.

> Nice.  Can you please split up the patch somehow? 

I'll remove the module loader fixes I have already submitted.
I'll separate out the changes to the existing files, and the Linux loader.

The majority of can't be easily split up into independent patches. Shall I 
split them up into a set of patches which have to be applied together?

> And please make sure you follow the GCS.

include/grub/arm/linux_setup.h is an unmodified file from Linux 2.6.9 

Uppercase is used thoughout for the name of RISC OS, as "risc_os" could be 
interpreted as a reference to the operating system called "riscos".

May I use the standard names for (ROM resident) C library globals?

May the official RISC OS system call names in include/grub/arm/RISC_OS/swis.h 
stay? The file is only included in assembler, and to change the names would 
be confusing.

Apart from a lack of comments and a few lower case macros, is there anything 
which obviously needs fixing?

> > What codes should the arrow keys return? The openfirmware and PC drivers
> > disagree.
> Perhaps it will be easier if there is one file that defines the
> available keys.  Now it is arch dependent.  Anyway, I remember there
> is some room for improvement...

I'll copy Open Firmware for now.

> > Possibly support attaching modules to the kernel.
> Attaching modules to the kernel?

Like grub-mkimage does on PCs.

Member AFFS, WYLUG, SWP (UK), ANL, RESPECT, Leeds SA, Leeds Anti-war coalition
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