Re: [PATCH] [RFCv3] add manpages for Memory Protection Keys

[Dave Hansen <dave.hansen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On 06/02/2016 05:25 PM, Michael Kerrisk (man-pages) wrote:
> The convention for man-pages is that new sentences always start 
> of new source lines. (This makes subsequent patches less "noisy", 
> since the common unit of change in a text is a sentence.)
> Could you fix this throughout please?

Yep, I can do that, and I'll also integrate all of your comments,
although I won't respond to all of them individually, I will integrate them.

>> +no longer be used in any protection-key-related operations.
>> +.PP
>> +.RB ( pkey_alloc ())
>> +.I flags
>> +may contain zero or more disable operations:
> 
> Why "zero or more" rather than "zero or one"? I mean:
> what sense could it make to OR together PKEY_DISABLE_ACCESS and
> PKEY_DISABLE_WRITE?

This is one of the attributes of the hardware that I carried up in to
the interfaces.  The hardware contains two bits: one to write-disable
and one to access-disable.  You're allowed to set both at the same time,
even though the "access" bit overrules the "write" bit when set.

So, it doesn't make a ton of logical sense with these two flags, but it
might if we ever got an "execute disable" feature or some other feature
that could be combined more arbitrarily.