Re: [Bugme-new] [Bug 9217] New: CONFIG_CMDLINE doesn't pass to kernel

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Sun, Oct 28, 2007 at 10:46:47PM +0000, Richard Purdie wrote:
> On Thu, 2007-10-25 at 22:54 +0100, Richard Purdie wrote:
> > On Thu, 2007-10-25 at 13:02 -0700, Andrew Morton wrote:
> > > It was in the inital report, at
> > > http://bugzilla.kernel.org/show_bug.cgi?id=9217 :
> >
> > This is the commandline they wanted to use, not the one that was
> > actually used. The one that was used should appear on the console, on
> > the serial console if they have the lead or in dmesg when the device
> > boots. We know it probably contained root=/dev/mtdblock2 but thats it.
> > 
> > I'd like to confirm which commandline is appearing since if we know
> > which one it is we might stand a chance of knowing where it came from,
> > until then this is just a guessing game.
> 
> There was a followup in the bugzilla:
> 
> > I use u-boot to boot kernel.
> > When kernel >=2.6.23 boot it use u-boot default bootparam:
> > console=ttyS0,115200 console=tty1 root=/dev/mtdblock2 rootfstype=jffs2
> > Now I try to change it in u-boot source.
> >
> > kernel 2.6.22.9 change default u-boot boot params to what I set in
> > CONFIG_CMDLINE But 2.6.23 and later doesn't
> 
> So its not the standard bootloader, its one which passes an ATAG
> commandline and 2.6.23 onwards uses an ATAG commandline if present
> over the compiled in commandline.

That statement is misleading.  The kernel has _always_ used the command
line passed from the boot loader in preference to the built-in command
line.

The thing that's changed is that the kernel how honors the value passed
from the boot loader in R2 to find out where the ATAG list is - as
documented since 2002 that it will eventually do.  That's 5 years
of warning.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of: