Question about xc_ptrace and PV domU process memory map.

[Necrosoft <necrosoft82@alice.it>]

Hi

I would use a xc_ptrace function to map a domU page having a guest 
virtual address. I use a PV domain, non HVM.

If I simply call xp_ptrace(xc_handle, PTRACE_PEEKTEXT, 0, virt_address, 
0) (where xc_handle is obtained by xc_handle = xc_interface_open() and 
first 0 is vcpu used) I receive this message:

"Could not allocate memory"

Reading the code I look that this error is caused by map_domain_va 
function (line 365 in xc_ptrace.c XEN 3.1). In this section of code is 
calculated total pages via:

long npgs = xc_get_tot_pages(xc_handle, current_domid);

I think that the error reported above is caused by a wrong value 
returned by xc_get_tot_pages function. In particular I think it is 
current_domid set incorrectly.

In effect current_domid is statically declared but I do not understand 
when and where is initialized.

So, the problem is pass the correct current_domid (in what way?) or I 
mistake something? You can help me?

TNX in advance!

Best regards