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

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
     1. no-watchdog
     2. watchdog=no
     3. watchdog=off

    Stacked inversions cancel each other: no-watchdog=no turns on the

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."

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.

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.

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