Re: [Xen-devel] [PATCH 0/6] grantable and address conversion patches

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 10 Apr 2006, at 10:34, Isaku Yamahata wrote:

> > 4/6: Make the function that fills in map/unmap requests arch-specific?
> > At least filling in host_addr should be arch-specific -- we don't
> > really want to overload dev_bus_addr like this.
> O.K. I'll introduce virt_to_host_addr() to xenLinux and make a new 
> patch.
> Is there any explanaition about host_addr and dev_bus_addr?
> When I wrote this patch,I guessed that host_addr should have been
> arch-indepedent and dev_bus_addr could be arch-depedent.
> But it was wrong. I couldn't find any good explaination/usage samples
> of these field.
Yes, the confusion is understandable. :-)  The host_addr indicates 
where in the guest's address space the mapping should be placed --- on 
x86 this is either a virtual address or the address of a PTE to be 
updated with the mapping, but you can make it what you like and 
pseudo-phys address sounds like a good idea. The name 'host_addr' is 
pretty crappy, I'm not sure why it was chosen. 'guest_addr' would be 
more accurate.
How about defining a function in gnttab.c or gnttab.h to fill in an 
entire map/unmap structure, and make the filling of host_addr dependent 
on XENFEAT_auto_translated_physmap? I think we would do the same thing 
for VP guest on x86 (fill host_addr with pseudo-phys addr rather than 
virtual addr).
 -- Keir


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