Re: [Xen-devel] Re: xc_translate_foreign_address() returns mfn??

To:	"Tim Deegan" <Tim.Deegan@xxxxxxxxxx>
Subject:	Re: [Xen-devel] Re: xc_translate_foreign_address() returns mfn??
From:	"Jun Koi" <junkoi2004@xxxxxxxxx>
Date:	Sat, 20 Dec 2008 08:40:08 +0900
Cc:	"List: Xen Developers" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On Sat, Dec 20, 2008 at 2:13 AM, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
> Hi,
>
> At 23:38 +0900 on 19 Dec (1229729882), Jun Koi wrote:
>> So everything indicates that xc_translate_foreign_address() actually
>> returns gfn, not mfn like in its comment. Could anybody confirms that
>> the function works well on both PV and HVM?
>
> To the best of my knowledge that function does not work at all for HVM
> (at least, I know it is broken when using 32-bit tools and 64-bit xen).
> I have a half-done patchset that cleans it up considerably, fixing HVM
> and compat issues, which I'll probably post at the end of the month.
>
> In any case, you are right: these functions (like _almost_ every other
> interface dealing with guest memory) deals in what in the shadow code are
> called GFNs.  That is, untranslated GPFNs for HVM guests, and MFNs for PV.
>
> The use of "mfn" in the source code is probably an indicator that this
> code pre-dates HVM guest support.

That is a smart guess, I think :-)

And please fix the comment to reflect this in your new code.

Many thanks,
J

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Re: [Xen-devel] Re: xc_translate_foreign_address() returns mfn??