[Xen-devel] Re: [patch 14/21] Xen-paravirt: Add XEN config options and disableunsupported config options.

[Keir Fraser <keir@xxxxxxxxxxxxx>]

On 16/2/07 10:09, "Andrew Morton" <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> Are the places where the domU code references machine addresses splattered
> all over the code?  If not, they can just be wrapped with
> preempt_disable/preempt_enable?

The main places where machine addresses are 'visible' are any code that
holds a pte_t,pmd_t,pud_t,pgd_t. We hide the machine-to-pseudophysical and
pseudophysical-to-machine translations inside e.g., pte_val() and __pte()
(i.e., constructors and extractors for page table entries). Obviously the
users of these macros are open coded all over the place, quite apart from
the performance cost of sprinkling preempt_{enable,disable} so liberally.

 -- Keir


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