For what it's worth, the 64-bit architecture, both prior to and with MIPS64,
has always required that 64-bit GPRs be sign-extended when used with 32-bit
operations. I'm surprised that this wasn't seen on more 64-bit CPUs than
just the SB1.
Michael Uhler, Chief Technology Officer
MIPS Technologies, Inc. Email: uhler at mips.com
1225 Charleston Road Voice: (650)567-5025
Mountain View, CA 94043
> -----Original Message-----
> From: firstname.lastname@example.org
> [mailto:email@example.com] On Behalf Of Ralf Baechle
> Sent: Tuesday, September 20, 2005 4:06 AM
> To: Matej Kupljen
> Cc: Maciej W. Rozycki; Daniel Jacobowitz; firstname.lastname@example.org
> Subject: Re: [PATCH] Fix TCP/UDP checksums on the Broadcom SB-1
> On Tue, Sep 20, 2005 at 01:00:04PM +0200, Matej Kupljen wrote:
> > > > This caused incorrect checksums in some UDP packets for
> NFS root.
> > > > The problem was mild when using a 10.0.1.x IP address,
> but severe
> > > > when using 192.168.1.x.
> > >
> > > Ah! So *that* is the reason for the absolutely abysmal NFS
> > > performance
> > > of the SWARM with 2.6! I have had no time to track it
> down -- thanks a
> > > lot!
> > Is this for MIPS64 only?
> > Because, on dbau1200 we also have poor NFS performance :-(
> It's for 64-bit kernels only. Note the difference, I didn't
> say MIPS64.
> Also, since this bug did result in an operation that has
> undefined behaviour it likely may will only have impacted
> some 64-bit processors - such as the SB1 - but others may
> have been unaffected.