am2 MBs - 4g + SCSI wipes out root partition

Gary Jennejohn gary.jennejohn at
Mon Oct 13 05:51:00 PDT 2008

On Mon, 13 Oct 2008 09:35:10 -0200
JoaoBR <joao at> wrote:

> On Saturday 11 October 2008 07:13:16 Jeremy Chadwick wrote:
> > It's a driver problem.  If you want to use SCSI then you'll have to limit
> > memory to 3.5 GB.

I probably should have written - it seems to be a problem with ahc.  In
general SCSI seems to work, as Scott has recently documented.  But see

> well indeed with less then 4G installed it works flawless, so the difference I 
> see is that former athln64 MBs had memory hole remap options or when 4Gig 
> installed they only gave 3.something to the OS even under amd64 - this is NOT 
> the case with the AM2 MBs which should support up to 8/16Mb onboard but wth 
> this amount freebsd amd64 does not even boot when a scsi adaptor is installed

I'm beginning to believe that it's motherboard/BIOS related and not a
general problem with ahc or any other SCSI driver.  I can say that
at least with my Gigabyte GA-M61P-S3 I observed data corruption with
4GB of memory installed and with the BIOS mapping a part of memory
above 4GB.

Forcing the kernel to use only 3.5GB solved the problem.

Gary Jennejohn

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