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Date: Tue, 06 May 2008 21:54:44 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
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Subject: Re: [Adeos-main] Advice regarding MIPS port
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To: Florent Audebert <f.audebert@domain.hid>
Cc: adeos-main@gna.org

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Florent Audebert wrote:
> Hi,
>=20
> I am starting to work on a Xenomai port for MIPS architecture as part

Cool!

> of an internship at Open Wide (France). It is my first real diving
> into the kernel sources so I'm far from being an expert. The goal of
> this project is to be able to run it on a Broadcom BCM6448 board.
>=20
> My first objective is to be able to run an Adeos patched kernel. I
> have decided to work with QEMU (mips-malta board emulation) instead of
> my real target since it provides me an easy way to use GDB and thus to
> understand a little bit more what is going on. Furthermore, it
> provides an easy way of testing it for other people since it only
> requires QEMU and no specific real hardware.

Yes, a reasonable approach for arch bring-up. Specifically when using
low-end targets, QEMU is able to provide faster debug round-trip times
than real hw.

>=20
> I read as much as documents I can (Life with Adeos, Porting Adeos,
> ...) and finally started messing with the code. I managed to compile a
> MIPS kernel merging common Adeos code from latest x86 patch and
> adapting (see below) / commenting out. I guess my kernel is far from
> functional. My current issue seems to be related to the timer (see
> attached file).
>=20
> Here is a list of explicit changes I have done so far :
>=20
>     - include/asm-mips/irqflags.h : added raw_local_*() and local_irq_*=
().
>     - include/asm-mips/irq.h : do_IRQ() calls __ipipe_handle_irq()
> instead of generic_handle_irq().
>     - arch/mips/kernel/ipipe.c : created __ipipe_do_IRQ() (used with
> __ipipe_enable_pipeline()) which calls generic_handle_irq().
>=20
> Do you think my approach is correct ? Are my few changes relevant ? I
> avoided to modify entry.S and genex.S, is this mandatory ?

I would be fairly surprised if you get away without touching them on
MIPS. Maybe you should study changes to those files (or comparable ones)
on other archs first - offline, but you may use QEMU here as well. Try
to understand some typical code paths from the hardware to the delivery
to some domain.

Jan


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