kern/133768: MONITOR PANIC: vcpu-0:VMM64 DoubleFault src=MONITOR @ rip=0xfffffffffc24e530 rsp=0xfffffffffc001000 regs=0xfffffffffc048f40 (0xfffffffffc24e9f1, 0xfffffffffc24e530)While Powering ON FreeBSD 7.1 -64bit guest with 64GB RAM

[Vishwas Karmalekar]

>Number:         133768
>Category:       kern
>Synopsis:       MONITOR PANIC: vcpu-0:VMM64 DoubleFault src=MONITOR @ rip=0xfffffffffc24e530 rsp=0xfffffffffc001000 regs=0xfffffffffc048f40 (0xfffffffffc24e9f1,0xfffffffffc24e530)While Powering ON FreeBSD 7.1 -64bit guest with 64GB RAM
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Apr 16 06:20:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Vishwas Karmalekar
>Release:        FreeBSD 7.1 - 32bit & 64bit
>Organization:
Patni Computer Systems Limited.
>Environment:
FreeBSD 7.1 -32bit

FreeBSD .vishwas.com 7.1-RELEASE FreeBSD 7.1-RELEASE #0: Thu Apr 16 01:18:34 IST 2009     root at .vishwas.com:/usr/src/sys/i386/compile/PAE  i386

>Description:
FreeBSD 7.1 - 32bit-

Configuring PAE in FreeBSD 6.3 & 7.1 systems follow different steps. 
In FreeBSD 7.1 -32bit, the PAE kernel configuration file is included with the distribution, one doesn't need to create it.
Steps that I followed-
cd /usr/src/sys/i386/conf 
config PAE 
cd ../compile/PAE 
make cleandepend && make depend 
make  
make install 
reboot
Systems works perfectly with 16GB RAM(This means PAE is working in the guest.)

* With 24GB & 32GB memory, system hangs & gives error-
  Panic : Page fault error.

* With 64GB of RAM, the system hangs & gives error-

MONITOR PANIC: vcpu-0:DoubleFault @ 0x4020:0xb91d8 (0xff0,0x1064) (0xb6cb8, 0xb9130)

FreeBSD 7.1 - 64bit
There are no issues uptil 24GB RAM.

* With 32GB RAM,  system hangs & gives error-
  Panic : Page fault error.

* With 64GB of RAM, the system hangs & gives error-

MONITOR PANIC: vcpu-0:VMM64 DoubleFault src=MONITOR @ rip=0xfffffffffc24e530 rsp=0xfffffffffc001000 regs=0xfffffffffc048f40 (0xfffffffffc24e9f1,0xfffffffffc24e530


My query is-
(1) 64GB works fine if PAE is enabled in 32bit FBSD 7.1 32bit?
(2) Am I making any mistake in executing steps.
(3) The reason behind Panic: Page fault
(4) The reason behinf Memory Panic
(5) Is this a OS related issue.


Please let me know the solution for the above issue.

Thanks in advance.

Vishwas

>How-To-Repeat:
If I change the RAM size to 16GB, both of the dead systems are UP & work very well. Ofcourse, it takes a large "UP time". (may be 10-15 mins)

If one changes the system ram to 64GB, the issue can be reproduced.
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: