some booting help

some booting help

[David Weis]

We've started again with the MCA rs/6000's and I needed a bit of help. A
little background on the machine-
It's a rs6000 7011-250 with a 601 PowerPC processor
The io ports on the MCA bus are addressed through a bus unit controller
with a BUID of 0x20. If I wanted to write something to 0x3f8 on the mca
bus, I would have to set up the segment register, etc, correct? Is this
something with enough overhead that I can't realistically do it for every
io port access?

We do have some code by Andrew Richardson that will make a valid boot disk
and print 987 to the display on the front. It's available at
http://www.sjdjweis.com/bboard/q-and-a-fetch-msg.tcl?msg_id=000005&topic_id=1&topic=RS%2f6000%20Linux

Any help is appreciated!

dave


--
David Weis                | 10520 New York Ave, Des Moines, IA 50322
djweis@plconline.com      | Voice 515-278-0133 Ext 231
                          | http://www.perfectionlearning.com/


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Re: some booting help

[David Edelsohn]

	I believe that AIX attaches and detaches from the I/O spaces for
every access.  It may try to cache values in one or more segment
registers, but not required that it be mapped continually -- if I remember
correctly.

David


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Re: some booting help

[David Weis]

On Fri, 12 May 2000, David Edelsohn wrote:
> 	I believe that AIX attaches and detaches from the I/O spaces for
> every access.  It may try to cache values in one or more segment
> registers, but not required that it be mapped continually -- if I remember
> correctly.

I was looking at the BUSIO_ATT and BUSIO_DET functions in
/usr/include/sys/adspace.h for clues. I had downloaded some AIX driver
source code examples once but can't seem to find them any more.

Thanks

dave


--
David Weis                | 10520 New York Ave, Des Moines, IA 50322
djweis@plconline.com      | Voice 515-278-0133 Ext 231
                          | http://www.perfectionlearning.com/


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Re: some booting help

[David Edelsohn]

>>>>> David Weis writes:

David> I was looking at the BUSIO_ATT and BUSIO_DET functions in
David> /usr/include/sys/adspace.h for clues. I had downloaded some AIX driver
David> source code examples once but can't seem to find them any more.

	See also /usr/include/sys/ioacc.h.  AIX device drivers accessing
those types of devices perform a lot of

iocc_val = IOCC_ATT(bus_id, 0);
val = BUSIO_GETC(iocc_val+XXX);
...
BUSIO_PUTC(iocc_val+XXX);
IOCC_DET(iocc_val);

	Plus programmed I/O, e.g., pio_assist().

David

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