i386/95106: cannot install freebsd

[Alexey]

>Number:         95106
>Category:       i386
>Synopsis:       cannot install freebsd
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Mar 30 12:30:23 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Alexey
>Release:        5.4, 6.0 6.1beta
>Organization:
>Environment:
>Description:
I'm unable to even boot the FreeBSD 5.4,6.0 and 6.1 install CD (i386 version).  I have an 
AMD Athlon XP 3000+ (333 MHz) with an Nvidia nForce 2 based motherboard (ASRock K7NF2-RAID) and 2x512Mb DDR 3200 module of memory. The boot cd dies with:
   panic: pmap_mapdev: couldn't alloc kernel virtual memory
This happens right after the agp0 load message.  I tried disabling ACPI with no luck.
>How-To-Repeat:

>Fix:
If I have one DDR 3200 512 Mb  - this problem disappears. If I have one DDR 3200 512 Mb and DDR 3200 256 Mb - no problem. If I have one DDR 3200 512 Mb, DDR 3200 256 Mb and DDR 3200 128 Mb - I have this problem.
>Release-Note:
>Audit-Trail:
>Unformatted: