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Re: port-hp700/35531: iee0 does not work on 735/99
The following reply was made to PR port-hp700/35531; it has been noted by GNATS.
From: Nick Hudson <nick.hudson%gmx.co.uk@localhost>
Subject: Re: port-hp700/35531: iee0 does not work on 735/99
Date: Mon, 4 May 2009 17:52:40 +0100
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:
> SZ715 C
> 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
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
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