Xen users - Nov 2014 - How does domU memory allocation work?

Hi,

I don't understand how Xen memory allocation works.

Suppose you create a HVM domU with:

maxmem = 3072
memory = 3072

Now, if I quey Xen I gen
* xl list:
    Name  ID   Mem VCPUs    State    Time(s)
    testvm   1  3067     1     -b----      12.8
* xenstore-ls:
    static-max = "3145728"
    target = "3137536"
     videoram = "8192"
*  xl top:
     MEM(k) MEM(%)  MAXMEM(k) MAXMEM(%)
     3141600        3.1         3146752              3.1

So, for the max memory, we have:

CFG_MAXMEM == XENSTORE_STATIC_MAX  <  XL_TOP_MAXMEM

While, for the current memory, we have:

XENSTORE_TARGET < XL_TOP_MEM < CFG_MEMORY < XL_LIST_MEM

I'm really confused.

Could you explain how it works?

Thank you very much.

Best,

-- Marco