Re: [Q] mfn_to_gmfn macro, log-dirty bitmap,

[Min Lee <min.lee@gatech.edu>]

Hi, thanks, but I don't understand.

dinfo->p2m_size:67584,
(XEN) addr:bff25000 accessible, mfn:5f8eb, gmfn:5f8eb
(XEN) addr:bff26000 accessible, mfn:6e003, gmfn:6e003
(XEN) addr:bff27000 accessible, mfn:425da, gmfn:425da

This domain has 256MB ram (67584 frames, slightly more than 65536) as 
p2m_size indicates, and I have dirty-bit bitmap which I believe has 67584 
bits. but In this case above, three frames has mfn of 0x5f8eb, 0x6e003, 
0x425da which I cannot use as index in my dirt_bit bitmap.
I understand PV guest directly use mfn into page table entry, but regarding 
log-dirt-bit  bitmap, I think I need gmfn index here.
Am I misunderstanding something?
What I'm doing is to read dirty bit for my virtual frame. so I need know 
which bit in log-dirty bit corresponds to my virtual frame.
Thanks
Min

On 6/28/2010 9:50 AM, Keir Fraser wrote:
> On 28/06/2010 14:40, "Min Lee"<min.lee@gatech.edu>  wrote:
>
>> I'm running 32bit PV-domu on 64bit xen&dom0 and I'm using
>> XEN_DOMCTL_SHADOW_OP_PEEK to get log-dirty bitmap.
>> First, I'm assuming this bitmap is indexed by gmfn, right? because we're
>> passing p2m->size parameter to xen.
>> Second, I have mfn (not gmfn) which I want to translate to gmfn so that I
>> can correctly read corresponding bit in log-dirty bitmap. so I've tried
>> mfn_to_gmfn() macro below but it doesn't seem to work. (always mfn==gmfn)
>> Maybe because m2p table is not enabled?
>> How can I properly do mfn_to_gmfn?
>
> For a PV guest, GMFN and MFN are equivalent.
>
>   -- Keir
>
>
>