Re: [Xen-devel] question about gmfn_to_mfn()

[tgh <tianguanhua@xxxxxxxxxx>]

Thank you all for all replys

In the HVM ,xen maintain guestos p2m table ,while in the paravirt ,guest 
maintain its own p2m,is it right?
Then in the paravirt case, if a VM's memory maxsize is 512M,and it is 
allocated 256M by "xm mem-set ",and it maybe only use 128M for running 
its OS and application , then what does its v2p table(or it is v2m talbe 
,I am not for sure) and p2m table look like in the aspect of size? and 
what about guestOS's mem_map size,is it 512M or 256M or 128M or 
something else?
another confusion for me is how does guestOS maitain its p2m table 
(linux has the v2p table ,but not p2m table),and what about the working 
procession for these tables?
could you help me
Thanks in advance








Keir Fraser åé:
> GPFN is guest machine frame number. It equals GPFN for fully-translated
> (e.g., HVM guests). It equals MFN for ordinary PV guests which maintain
> their own p2m translation table.
>
>  -- Keir
>
>
> On 23/3/07 06:56, "Guy Zana" <guy@xxxxxxxxxxxx> wrote:
>
>   
> > mfn = machine frame number, it is an index to a page in the real memory of the
> > system.
> > gmfn = guest's machine frame number and it sometimes called gpfn or just pfn.
> > Guests have a translation table between their own virtualized pseudo physical
> > memory and the real machine memory -> this is exactly what gmfn_to_mfn does.
> > Pfn is a generic term that might be used in all kind of situations so you
> > should understand from the context.
> >
> > Guy. 
> >
> >     
> > > -----Original Message-----
> > > From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> > > [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of tgh
> > > Sent: Friday, March 23, 2007 5:31 AM
> > > To: xen-devel@xxxxxxxxxxxxxxxxxxx
> > > Subject: [Xen-devel] question about gmfn_to_mfn()
> > >
> > > hi
> > >  I read the code of balloon part,  I am  confused about  the
> > > meaning and function of " mfn = gmfn_to_mfn(d, gmfn);"
> > >  what is gmfn  and  and what is mfn?  and" #define gmfn_to_mfn(_d,
> > > gpfn)  mfn_x(sh_gfn_to_mfn(_d, gpfn))"
> > > it seems that  gmfn and gpfn  is the same  or  what is the
> > > trick in it ?
> > >
> > > I am confused about it
> > >
> > > could you help me
> > > Thanks in advance
> > >
> > >
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xen-devel
> > >
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> >     
>
>
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