[Xen-devel] Re: [PATCH] Support swap a page from user space tools -- Was RE: [RFC][PATCH] Basic support for page offline

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

Hi, 

At 05:12 +0000 on 19 Mar (1237439530), Jiang, Yunhong wrote:
> > - You're passing a physical address (of the PTE to update) in an MFN
> >   field.  That's not going to be big enough on all platforms.  Also   it's
> > pretty confusing. 
> 
> Yes, fixed and now named pte_addr as a uint64.

You made it an unsigned long, which is still smaller than a paddr_t on
PAE builds.  And you can't just make it 64 bits in that union without
breaking the ABI; you'll need to add a new interface somewhere.  Maybe
Keir can suggest a better place.

> I missed one thing in previous patch, i.e. the changes to
> xc_core_arch_map_p2m().  Originally I change that function to map the
> p2m table as rw (it is forgoted in previous mail). Now I add a new
> function xc_core_arch_map_p2m_writable() so that not break the
> original API.

OK.  Are there any callers of the xc_core_arch_map_p2m() that would care
if it gave a writable mapping?

> But I'm a bit confused why the xc_domain_save.c will not use this
> function to map p2m table also? Instead, I noticed a lot of duplicate
> on these two files, I can send out a clean patch in future if it is
> ok.

I think that was just carelessness at the time the xc_core stuff went in
(and possibly also distaste at the rather scruffy state of the
xc_domain_save version).  They should probably be unified at some point
if anyone has the energy. :)

Cheers,

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]

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