Re: [Xen-devel] [PATCH 1/3] cmdline_parse: Also pass bool_assert to OPT_CUSTOM so that parse_bool can be used correctly.

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 07/28/14 12:23, Andrew Cooper wrote:
> On 28/07/14 17:18, Don Slutz wrote:
> > On 07/28/14 12:08, Andrew Cooper wrote:
> > > On 28/07/14 16:59, Don Slutz wrote:
> > > > Based on:
> > > >
> > > > commit 2fcb51bc7a4fcb7534265d7bb155c6ddf03952b8
> > > > Author:kfraser@xxxxxxxxxxxxxxxxxxxxx  <kfraser@xxxxxxxxxxxxxxxxxxxxx>
> > > > Date:   Mon Jul 9 14:29:53 2007 +0100
> > > >
> > > >      Also allow boolean cmdline params to be inverted in two other ways.
> > > >
> > > >      Now, a standard boolean (e.g., watchdog) can be inverted in three
> > > >      ways:
> > > >       1. no-watchdog
> > > >       2. watchdog=no
> > > >       3. watchdog=off
> > > >
> > > >      Stacked inversions cancel each other: no-watchdog=no turns on the
> > > >      watchdog.
> > > >
> > > > bool_assert is needed to do stacked inversions with parse_bool.
> > > >
> > > > Signed-off-by: Don Slutz<dslutz@xxxxxxxxxxx>
> > > Why do we need to care about stacked inversions?
> > >
> > > From xen-command-line.markdown:
> > >
> > > "Explicitly specifying any value other than those listed above is 
> > > undefined, as is stacking a |no-| prefix with an explicit value."

Ah, I see that:


commit 6328e728f6d6589a10d7e9f97a47f566f63743c2
Author: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>
Date:   Mon Sep 3 11:22:00 2012 +0100

    docs/command line: Clarify the behavior with invalid input.

    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxx>
    Committed-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

was when this changed.

> > The command line:
> >
> > no-console_timestamps dom0_mem=3G loglvl=all guest_loglvl=all 
> > com1=9600,8n1 console=com1 crashkernel=256M@256M no-console_timestamps=no
> > in 4.4 and before ends up with date style console_timestamps. In xen 
> > 4.5 you get no console_timestamps.
> > The simpler case of no-console_timestamps no longer works also.
> >
> >    -Don Slutz
> Ok, so my "compat for older console_timestamp boolparam" needs 
> improving a bit.
Yes, that is what patch #2 does.


> However, "no-console_timestamps=no" is undefined, and we make no 
> guarentees as to what happens if you give repeated (different) command 
> line options to Xen.  Both of these are user/admin error and should 
> not be worked around in Xen code.
> ~Andrew
Ok,  I was not aware of this change in "defined" behavior.  I will 
re-work this
to include Jan's 'pass "no" if "no-" removed.'

   -Don Slutz


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