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subpage_prot.2: Improvements after review by Paul Mackerras 

Reported-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2010-10-30 07:15:38 +02:00
parent 840922217c
commit c079ed6486
1 changed files with 10 additions and 9 deletions
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19
man2/subpage_prot.2
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@ -62,7 +62,7 @@ Each 2-bit field in the protection map is either 0 to allow any access,
On success,
.BR subpage_prot ()
returns 0.
Otherwise, one of the negated error codes specified below is returned.
Otherwise, one of the error codes specified below is returned.
.SH ERRORS
.TP
.B EINVAL
@ -108,14 +108,15 @@ to apply to a specified range of virtual addresses.
These masks are applied at the level where hardware page-table entries (PTEs)
are inserted into the hardware page table based on the Linux PTEs,
so the Linux PTEs are not affected.
.\" Perhaps we don't need to document this implementation detail:
.\"
.\" Implicit in this is that the regions of the address space that are
.\" protected are switched to use 4k hardware pages rather than 64k
.\" hardware pages (on machines with hardware 64k page support).
.\" In fact the whole process is switched to use 4k hardware pages when the
.\" subpage_prot system call is used, but this could be improved in future
.\" to switch only the affected segments.
Implicit in this is that the regions of the address space that are
protected are switched to use 4-kB hardware pages rather than 64-kB
hardware pages (on machines with hardware 64-kB page support).
.\" In the initial implementation, it was the case that:
.\" In fact the whole process is switched to use 4k hardware pages when the
.\" subpage_prot system call is used, but this could be improved in future
.\" to switch only the affected segments.
.\" But Paul Mackerass says (Oct 2010): I'm pretty sure we now only switch
.\" the affected segment, not the whole process.
.SH SEE ALSO
.BR mprotect (2),
.BR syscall (2);