Re: port-hp700/35531: iee0 does not work on 735/99

[Nick Hudson <nick.hudson%gmx.co.uk@localhost>]

On Sunday 03 May 2009 11:35:03 Izumi Tsutsui wrote:
>  The major difference between Step-A and B/C is 32 bit big endian mode
>  enabled by IEE_SYSBUS_BE bit. On rev A chip, we have to treats
>  all 32 bit pointers in DMA descriptors as two 16-bit big endian entities
>  as well as the SCP pointer.
>
>  My 735/125 seems to have Rev C chip as the following:
>
>   KU82596DX-33
>   L4502047
>   SZ715 C
>   INTEL(M)(C)1989
>
>  but now it also works in Rev A compatible mode (i.e. without
> IEE_SYSBUS_BE) with the attached patch, so it should also work on Rev A
> chips.

This is cool! Thanks for working on this.

I've tested this on my 715/50 against netbsd-5 as I've got too many changes in 
my -current source trees :)

>  As noted in comments, it might be better to detect chip revision
>  and switch flags at runtime, but I can't find how we ca do it
>  in the Intel manual.

Is it worth running IEE_SYSBUS_BE at all? Is there a big performance impact on 
the machines with rev C chips? If there isn't a big hit I'd say we just use 
iee(4) without IEE_SYSBUS_BE on hppa.

>  ---
>  Izumi Tsutsui

Thanks,
Nick