am2 MBs - 4g + SCSI wipes out root partition

Dieter freebsd at
Mon Oct 13 16:25:56 UTC 2008

> > It sounds as if there's an implementation/design problem either in
> > FreeBSD's hardware compatibility support for AM2 (probably something
> > very low-level) systems, or there is a bug with these Gigabyte boards;
> good, but it is not only gigabyte, I experienced it on Asus, Abit, Epox and=
> =20
> MSI  =20

Perhaps something common in the firmware/BIOS ?

> all this MBs have in common that when 4Gig is installed the full 4gig are=20
> avaliable to the Os, on former S939 arquitecture, depending on mem hole=20
> remapping setting in BIOS there was +/-3.5gig or 4.+Gig  available for amd6=
> 4,=20
> mostly the remapping feature was not existent and then there was always=20
> +/-3.5 Gig available

Is there some debugging flag to turn on that shows what the firmware/BIOS
says about addresses, and the final address map (both RAM and I/O devices)
as used by FreeBSD?

> > it could be either, or possibly both.  It might work in Linux because,
> > for all we know, Linux may have workarounds in place for whatever the
> > problem may be.  We simply do not know at this point.

IIUC, Linux uses the firmware/BIOS as little as possible and does
everything itself.  Which is why *BSD can't run on LinuxBIOS.

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