data corruption with ahc driver and 4GB of memory using a FBSD-8 64-bit installation?

[Scott Long]

Gary Jennejohn wrote:
> I think $(subject) says it all.
> 
> I have a Gigabyte AM2 mobo with an AMD64 X2 CPU installed.
> 
> The SCIS set up looks lie this:
> 
> 29160N <--> da0 <--> da1
> 
> da0 has a 32-bit installation of FBSD-8
> da1 has a 64-bit installtion of FBSD-8
> 
> If I install 4GB of memory (4 DIMMs) in the system I see the following
> behavior:
> 
> a) booting from da0 works just fine and I can access both disks without
> any problem.
> 
> b) booting from da1 results in (apparent) data errors such that /bin/sh
> dies with SIGILL and /rescue/sh dies with SIGSEGV.
> 
> c) trying to do an installation of a snapshot of FBSD-8 to a SCSI disk
> results in various problems, among others a kernel panic in ffs_balloc
> during newfs.
> 
> d) an installation to a SATA disk succeeds and the system runs just
> fine.
> 
> With only 3GB of memory everything works. Of course, I'd really like to
> be able to use the entire 4GB. And I want to keep my SCSI disks.
> 
> I suspect that ahc has some sort of problem in 64-bit mode. However,
> I'm not certain whether the 32-bit installation works with 4GB simply
> because the ahc driver uses bounce buffers.
> 
> Has anybody else seen this? Can anyone confirm that ahc does indeed
> have an error with 4GB and a 64-bit installation?
> 
> BTW please put me in the Cc because I'm not subscribed to this ML.
> 

The ahc driver should work with >4GB, and in fact that was a standard
part of the test suite back when it was still in active development.  If
it doesn't work now then it's due to some sort of bitrot.  I can try to
test and debug it myself, but I'm pretty overcommitted so I can't
guarantee that I'll get to it.  If others would like to help test and
debug, I'm happy to answer questions and provide assistance.

Scott