svn commit: r240067 - head/sys/kern

[Aleksandr Rybalko]

On Mon, 3 Sep 2012 12:29:05 -0700
Garrett Cooper <yanegomi at gmail.com> wrote:

>> On Mon, Sep 3, 2012 at 2:23 AM, Aleksandr Rybalko <ray at freebsd.org>
>> wrote:
>> > On Mon, 3 Sep 2012 02:05:15 -0700
>> > Garrett Cooper <yanegomi at gmail.com> wrote:
>> >
>> >>> On Sep 3, 2012, at 1:52 AM, Aleksandr Rybalko wrote:
>> >>>
>> >>> > Author: ray
>> >>> > Date: Mon Sep  3 08:52:05 2012
>> >>> > New Revision: 240067
>> >>> > URL: http://svn.freebsd.org/changeset/base/240067
>> >>> >
>> >>> > Log:
>> >>> >  Add kern.hintmode sysctl variable to show current state of
>> >>> > hints: 0 - loader hints in environment only;
>> >>> >  1 - static hints only
>> >>> >  2 - fallback mode (Dynamic KENV with fallback to kernel
>> >>> > environment) Add kern.hintmode write handler, accept only
>> >>> > value 2. That will switch static KENV to dynamic. So it will
>> >>> > be possible to change device hints.
>> >>>
>> >>> ...
>> >>>
>> >>> > +  /* Migrate from static to dynamic hints */
>> >>> > +  switch (hintmode) {
>> >>> > +  case 0:
>> >>> > +          if (dynamic_kenv)
>> >>> > +                  /* Already here */
>> >>> > +                  hintmode = value; /* XXX: Need we switch
>> >>> > or not ? */
>> >>> > +                  return (0);
>> >>>
>> >>> ^^^^ typo (missing braces)? ^^^^
>> >
>> > Ohhh, yeah, testing now.
>> > Thank you!
>> >
>> >>>
>> >>> Also, don't you need extra glue for jails?
>> >
>> > Why, jails uses separate hints/kenv?
>> 
>> I was wondering whether or not the tunables could be changed from the
>> jail, thus allowing someone to affect the host system or if this
>> memory space was effectively CoWed in some way, shape or form.

Think after switch hints will be controlled by the same policy as
before. Normal hints 0-16KB, so it will not be big memory waste.
Handler allow to do it only one time: user set it to 2, handler copy
env. Next time any just check, if 2, do nothing.

You think better to add CTLFLAG_PRISON flag, to hide it from jails?

>> 
>> Thanks!
>> -Garrett

Thank you Garrett!

WBW
-- 
Aleksandr Rybalko <ray at freebsd.org>