RE: [Xen-users] amd64 system only seeing 3.5gb instead of 4gb of memory

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> 
> Further to what has already been said (all of which is sensible and
good
> suggestions):
> 1. Assuming you have an AMD processor, you need a procesor that is Rev
E
> or later.

First half of cat /proc/cpuinfo:

processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 67
model name      : Dual-Core AMD Opteron(tm) Processor 1210
stepping        : 3
cpu MHz         : 1800.018
cache size      : 1024 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36
clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext
3dnow pni cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips        : 4501.72
TLB size        : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc

40 bits of physical addressing should be enough shouldn't it? Or are you
talking about revision E being required for the remapping?

> 2. You need to have PAE or 64-bit mode to see any memory ABOVE 4GB (so
> even if it's remapped, non-PAE will not be able to "get there" because
> it's strictly limited to 32-bit memory addresses, which is 4GB in
total
> - this is why the PCI memory is located around the end of 4GB).

xm info:

host                   : dev
release                : 2.6.18-4-xen-amd64
version                : #1 SMP Fri May 4 02:40:51 UTC 2007
machine                : x86_64
nr_cpus                : 2

definitely running in 64 bit mode yes?

> 3. Your BIOS must enable "memory hoisting", which is the techie name
for
> "move memory from under PCI space to someplace else".

Now this I haven't checked... I'll have a look this weekend.

Subsequent reading showed at least one other person had such a problem,
and it was probably related to grub passing a 'basic' memory map instead
of the modern type (I even followed up to that post originally... what a
short memory I have these days!!!). I can probably confirm this from xm
dmesg:

(XEN) Command line: /xen-3.1.0-1-amd64.gz
(XEN)  0000000000000000 - 000000000009f000 (usable)
(XEN)  0000000000100000 - 00000000dfff0000 (usable)
(XEN) System RAM: 3583MB (3669564kB)
(XEN) Xen heap: 13MB (14176kB)
(XEN) Domain heap initialised: DMA width 32 bits

D'oh!

I'll try and get into the office this weekend and have a better look.
There are no BIOS upgrades at this point.

Thanks

James

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