am2 MBs - 4g + SCSI wipes out root partition

[Tom Evans]

On Mon, 2008-10-13 at 09:37 -0200, JoaoBR wrote:
> On Saturday 11 October 2008 13:26:29 Adam McDougall wrote:
> > Jeremy Chadwick wrote:
> > > On Sat, Oct 11, 2008 at 04:45:29PM +0200, Gary Jennejohn wrote:
> > >> On Sat, 11 Oct 2008 03:13:16 -0700
> > >>
> > >> Jeremy Chadwick <koitsu at FreeBSD.org> wrote:
> > >>> On Sat, Oct 11, 2008 at 11:30:57AM +0200, Gary Jennejohn wrote:
> > >>>> On Fri, 10 Oct 2008 14:29:37 -0300
> > >>>>
> > >>>> JoaoBR <joao at matik.com.br> wrote:
> > >>>>> I tried MBs as Asus, Abit and Gigabyte all same result
> > >>>>>
> > >>>>> Same hardware with SATA works perfect
> > >>>>>
> > >>>>> Same hardware with scsi up to 3.5Gigs installed works perfect
> > >>>>>
> > >>>>> what calls my attention that all this MBs do not have the memroy hole
> > >>>>> remapping feature so the complete 4gigs are available what normally
> > >>>>> was not the case with amd64 Mbs for the Athlon 64 CPUs
> > >>>>>
> > >>>>> some has an opinion if this is a freebsd issue or MB falure or scsi
> > >>>>> drv problem?
> > >>>>
> > >>>> It's a driver problem.  If you want to use SCSI then you'll have to
> > >>>> limit memory to 3.5 GB.
> > >>>
> > >>> What you're saying is that Adaptec and LSI Logic SCSI controllers
> > >>> behave badly (and can cause data loss) on amd64 systems which contain
> > >>> more than 3.5GB of RAM.  This is a very big claim.
> > >>>
> > >>> Have you talked to Scott Long about this?
> > >>>
> > >>> Please expand on this, and provide evidence or references.  I need to
> > >>> document this in my Wiki if it is indeed true.
> > >>
> > >> See the freebsd-scsi thread with Subject "data corruption with ahc
> > >> driver and 4GB of memory using a FBSD-8 64-bit installation?" from Wed,
> > >> 30 Jan 2008.
> > >>
> > >> This was for ahc, but the bit-rot which Scott mentions in his reply
> > >> might also apply to the LSI Logic controllers.
> > >>
> > >> Basically the driver doesn't correctly handle DMA above 4GB.  Since the
> > >> PCI hole gets mapped above 4GB it causes problems.  the (S)ATA drivers
> > >> don't seem to have this problem.
> > >
> > > Thank you -- this is the exact information I was looking for.
> > >
> > > I will update my Wiki page to reflect this quite major problem.
> >
> > I am using some LSI (mpt driver) ultra4 (U320 scsi) and LSI SAS
> > controllers in FreeBSD 7.x amd64 with 20G of ram, and Adaptec (aac
> > driver) with a 5th generation RAID card with 8G of ram, both have no
> > such corruption problems.  Providing this as a counter-example just to
> > document some evidence of which products seem to work fine.
> > _______________________________________________
> 
> 
> well this for sure is NOT a AM2 MB but any server MB which indeed run fine as 
> Tyans, SMs and others I guess
> 

It sounds like your issue is specific to certain motherboards and BIOS,
which would be non driver specific. Unless this is something that can be
worked around, I think the 'solution' is that with this hardware, you
are limited to 3.5 GB RAM. 

Perhaps different SoHo boards would provide different behaviour...

Cheers

Tom
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