[PATCH 0/2] [Maverick] kernel-maverick-upstart: pass entire command line to init

[Andy Whitcroft]

On Thu, Jun 17, 2010 at 07:11:38AM -0600, Tim Gardner wrote:
> On 06/17/2010 03:46 AM, Andy Whitcroft wrote:
> >As part of the blueprint kernel-maverick-upstart[1] we have been
> >investigating passing all of the kernel command line to init.  This allows
> >upstart to know everything that was passed so that we can share options,
> >for example quiet.
> >
> >Below are sample options list as dumped by an additional debugging patch.
> >In each case the orginal boot line is the same.  With the option disabled,
> >ie. normal boot semantics:
> >
> >     [    0.000000] environ<BOOT_IMAGE=/boot/vmlinuz-2.6.34-4-generic>
> >     [    0.000000] argument<splash>
> >
> >With the option enabled:
> >
> >     [    0.000000] environ<BOOT_IMAGE=/boot/vmlinuz-2.6.34-4-generic>
> >     [    0.000000] environ<root=UUID=bb5209a0-aca5-49da-b99b-52eff65f986b>
> >     [    0.000000] argument<ro>
> >     [    0.000000] argument<quiet>
> >     [    0.000000] argument<splash>
> >
> >Note that the semantics of init=foo<arg>  <arg>  ... are unchanged.
> >
> >The following patch set implements this for Maverick.  Proposing for
> >Maverick.
> >
> >-apw
> >
> >[1] http://blueprints.launchpad.net/ubuntu/+spec/kernel-maverick-upstart
> >
> >Andy Whitcroft (2):
> >   UBUNTU: SAUCE: add option to hand off all kernel parameters to init
> >   UBUNTU: [Config] enable passing all kernel command line to init
> >
> >  debian.master/config/config.common.ubuntu |    1 +
> >  include/linux/moduleparam.h               |    2 +-
> >  init/Kconfig                              |    7 ++++++
> >  init/main.c                               |   33 ++++++++++++++++++++++------
> >  kernel/params.c                           |   20 ++++++++++++-----
> >  5 files changed, 49 insertions(+), 14 deletions(-)
> >
> >
> 
> So this is likely an option I want disabled for the backports to
> Lucid, right?
> 
> There isn't a lot of information in the spec or your commit log
> about the real reason for this patch, other then its more convenient
> for upstart to have command line items pre-parsed. Is there a more
> fundamental reason?

As I understand it it allows upstart to respond to 'quiet' correctly and
earlier.  I think there is a fundamental issue for upstart that to get
all the options (currently) it has to mount /proc and then read
/proc/cmdline.  But you may want to have verbosity on for that section
but upstart cannot tell until its mounted it.  Catch-22.

I am not 100% sure, but I suspect there would be no issue for older
upstart based systems should they have this enabled or not.

-apw