Re: [Xen-devel] Hypercall interface changes for PAE

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 1 Jun 2005, at 10:30, Ian Pratt wrote:

> The inner most guts of the domain builder where we build the 
> pagetables,
> it's probably best to have two totally separate functions as there are
> significant differences between the PAE and non PAE initial pagetables.
>
> For the save/restore functions I'd like to share the source code.
> However, it would be very ugly indeed to butcher the code such that the
> same compiled code can run-time switch. I think the best soloution is
> just to run it through the compiler twice with different header files.
> [Aside: we need to give the save/restore code the same treatment that
> the improved pte typing patch gave to Xen.]
Restructuring the code so that the minimal amount of stuff has to be 
double-compiled will not be very difficult. Just anything that looks at 
or modifies pagetable entries, pretty much. There really isn't that 
much p.t. code in libxc -- just a few hundred lines total I would say.
But I think just making everything u64 (both ptr and val in 
mmu_update_t, and val in update_va_mapping) is simple, won;t hurt 
performance, and probably makes the tools code a bit simpler to read 
and to build. So let's just do that then and argue about something more 
important. :-)
 -- Keir


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