Re: [Xen-devel] mini-os: arm: grant mapping

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Ian Campbell, le Mon 22 Sep 2014 12:09:16 +0100, a Ãcrit :
> On Mon, 2014-09-22 at 11:01 +0000, Dave Scott wrote:
> > I also noticed that the x86 version initialises the âdemand mapping
> > areaâ from âmax_pfnâ in mm.c. Iâm a bit suspicious about this on arm
> > since the grant table is being mapped in somewhere pre-ordained in the
> > device tree (If Iâm reading it correctly) and there could be an
> > overlap (if weâre unlucky).
> 
> AIUI the demand mapping is for the domains own allocated memory (similar
> to COW/allocate-OW memory on a normal Unix process), not for grant
> mappings, but I may be confused.

No, we only implement COW for anonymous mmap and the BSS. "demand
mapping area" is for getting virtual address space, which is used for
mapping all kinds of things (mmap, ioremap, and here, grants).

Samuel

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