MPC8xx enhancements

Joel Sherrill joel.sherrill at
Sun Oct 21 15:25:34 UTC 2001

This really should be discussed on the mailing list because
it impacts a lot more users than you think.

First, I think this is a good thing.

My general rule of thumb is that you should add capabilities
without breaking the current BSPs.  That means leaving the
current settings as defaults and/or modifying the existing
in-tree BSPs to provide proper settings.  In the case of
the 8xx, you should also provide instructions on what to
do to existing out-of-tree BSPs to keep current.


"Artemii S. Ivanov" wrote:
> Hello, Joel!
> I have stumbled with some problems during MPC860
> RTEMS bsp development. I use eth_comm, and mbx8xx bsps, as
> basis for work...
> 1). console-genric.c (libcpu/powerpc/m8xx/) looks as not
> quite generic...
>    a).Different boards could use differnt ports configurations
>    (e.g. RXD3/4 could be achieved via port A, or port D), some chips(line
>    drivers) need additional signals...
>    b). Baud Rate Generators distribution between SCCs.
>    console-generic driver supports BRG allocation routine internally,
>    but there could be BRG conflict between console and other dirvers that
>    use SCC (e.g. Ethernet).
>    c). console-generic code could be significately reduced.
> 2). Generic ethenet driver.
>     It seems that one could use generic ethernet driver (based on
>     network.c from mbx8xx for example) with some improvements
>     (see items a).b).c). from 1).)
> 3). Mmu initialization.
>     Instruction and Data mmu initialization should be separated -
>     Different memory attributes could be used.
>     (currently Instruction and Data MMU use fill the same registers values
>     from MMU_TLB_table).
> We're going to submit new variants for console and ethernet dirver, but
> it arise some questions: what should be done for bsp that use current
> drivers? should create new_console, new_mmu in order to save old variant,
> or rewrite(remove) current m8xx bsp?
> Waiting for your comments.
> Thank you.
> Artemii S Ivanov.
> Oktet Ltd. Russia.

Joel Sherrill, Ph.D.             Director of Research & Development
joel at                 On-Line Applications Research
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