Fresh Debian Squeeze (6) Installation - Very High Ram Usage
We have a Dell Poweredge R210 server with 8GB of installed RAM. This is a fresh install of Debian Squeeze, with pretty much only build-essentials and Xen 4.0.1 installed through aptitude. The kernel version is 2.6.32-5-xen-amd64.
1GB of our memory is "absent", and is not available and the output of
dmesg | grep Memory is:
[ 2.069861] Memory: 6842924k/8132468k available (3147k kernel code, 1058596k absent, 230948k reserved, 1908k data, 600k init)
Here is the output of
total used free shared buffers cached Mem: 7195 1349 5846 0 3 28 -/+ buffers/cache: 1316 5878 Swap: 3813 0 3813
Whereas, if I use the original kernel (2.6.32-5-amd64), I have access to the full 8GB, despite 1GB still being absent - note the 9.5GB(!) apparently available:
[ 0.000000] Memory: 8177956k/9437184k available (3079k kernel code, 1058596k absent, 200632k reserved, 1892k data, 592k init)
total used free shared buffers cached Mem: 7995 91 7904 0 2 22 -/+ buffers/cache: 66 7929 Swap: 3813 0 3813
I am aware of the situation of absent memory being basically memory holes in the memory map https://bugzilla.redhat.com/show_bug.cgi?id=598290 - but why would a different kernel on the same hardware show such different behaviour?
So, my questions are:
1) Is this likely to be a kernel bug, and therefore should I report it?
2) Is there any hope for recovering the memory, or find out how / why the Xen kernel has taken it and fix it?
Thanks for any help!