Messages in this thread | | | Date | Fri, 23 Jan 2009 13:05:27 -0800 | From | Jeremy Fitzhardinge <> | Subject | Re: [Xen-devel] [PATCH 2/2] x86: add pte_set_flags/clear_flags for pteflag manipulation |
| |
Jan Beulich wrote: > I think a comment (or event a BUG_ON()) should be added here to make > clear that this absolutely must not be used to toggle the present bit. I > even view toggling _PAGE_PSE as dangerous this way. > > And alternative would be to make these macros and #undef them (or keep > them inline functions but add destructive #define-s) after all their users. >
I don't see any particular problem with changing PSE or even Present with these functions; they don't operate on live in-memory ptes, so its not like they could ever be used to modify a pte unless followed with some kind of set_pte operation. It is unwise to change any pte flag without knowing what you're doing (though P or PSE would probably have less subtle effects than some of the others).
But it probably wouldn't hurt to have a __ prefix to indicate they're "internal" and not for general use.
J
| |