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

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

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>
To: gnats-bugs%netbsd.org@localhost
Cc: port-hp700-maintainer%netbsd.org@localhost,
 gnats-admin%netbsd.org@localhost,
 netbsd-bugs%netbsd.org@localhost,
 root%garbled.net@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:
 >
 >   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