Generic problem with BootX

Generic problem with BootX

[Benjamin Herrenschmidt]

I think I finally found the cause of the crash: During relocation of the
kernel by BootX, it looks like the UW is still DMA-ing things to main
memory, damaging the kernel. I added a reset of the Symbios chip just
before switching the MMU off, and now, my kernel boots again on the G3.

This is a generic problem with any device that may do DMA. I thought most
of this would be fixed by the shutdown-proc mecanism used in bootx, but
apparently, this is not the case.

So, I'll soon release a version of BootX that resets this card before
booting, and also resets all the DBDMA channels (could someone send me a
list of all possible DBDMA channels on various chips ? I think I know
where the mac-io ones are, but I don't have a Grand-Central not OHare
based machine available now).

I beleive I also need to reset an eventual adaptec board, and BootX will
probably require similar fixes for all sorts of boards (fortunately,
boards that DMA to system memory all the time even after a MacOS shutdown
are quite rare).

If you know of a device that may fall in this category, please send me
enough infos for me to reset it (device-tree name, how to reset it, etc...)


-- 
           E-Mail: <mailto:bh40@calva.net>
BenH.      Web   : <http://calvaweb.calvacom.fr/bh40/>





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Re: Generic problem with BootX

[David A. Gatwood]

On Mon, 22 Mar 1999, Benjamin Herrenschmidt wrote:

> I think I finally found the cause of the crash: During relocation of the
> kernel by BootX, it looks like the UW is still DMA-ing things to main
> memory, damaging the kernel. I added a reset of the Symbios chip just
> before switching the MMU off, and now, my kernel boots again on the G3.
> 
> This is a generic problem with any device that may do DMA. I thought most
> of this would be fixed by the shutdown-proc mecanism used in bootx, but
> apparently, this is not the case.
> 
> So, I'll soon release a version of BootX that resets this card before
> booting, and also resets all the DBDMA channels (could someone send me a
> list of all possible DBDMA channels on various chips ? I think I know
> where the mac-io ones are, but I don't have a Grand-Central not OHare
> based machine available now).

Please, if you do this, please make it do a similar reset before booting
MkLinux.  The stock G3 UW cards have been a thorn in our side for the same
reason.


Later,
David

David A. Gatwood                         Visit globegate's internet
dgatwood@globegate.utm.edu                  talker, Deep Space 36
http://globegate.utm.edu                telnet globegate.utm.edu:9624


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Re: Generic problem with BootX

[Benjamin Herrenschmidt]

On Mon, Mar 22, 1999, David A. Gatwood <marsmail@globegate.utm.edu> wrote:

>Please, if you do this, please make it do a similar reset before booting
>MkLinux.  The stock G3 UW cards have been a thorn in our side for the same
>reason.

Unfortunately, I can't do that easily without having the source code for
MkLinux booter. I cannot reset the NCR chip before running the MkLinux
booter plugin since this must be done _very_ late in the boot process. I
may be able to patch it since it's 68k code but this will definitely take
time.


-- 
           E-Mail: <mailto:bh40@calva.net>
BenH.      Web   : <http://calvaweb.calvacom.fr/bh40/>





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