[PATCH] arm/imx: use Kconfig choice for low-level debug UART selection

Nicolas Pitre nicolas.pitre at linaro.org
Sun Aug 21 14:28:46 EDT 2011

On Sun, 21 Aug 2011, Russell King - ARM Linux wrote:

> On Sun, Aug 21, 2011 at 01:59:44PM -0400, Nicolas Pitre wrote:
> > On Sun, 21 Aug 2011, Russell King - ARM Linux wrote:
> > > I never liked the idea of coupling this into earlyprintk - and I think
> > > I said so at the time.  I'll say it again:
> > > 
> > > The LL DEBUG stuff is there to be able to do low level "it won't boot"
> > > debugging.  It's not there as a user option.  You are supposed to know
> > > exactly what you are doing when using the option.
> > > 
> > > If we're going to start having earlyprintk be an argument against this,
> > > I'll simply rip out the earlyprintk coupling to LL debug, and people
> > > can go back to patching printk.c to make this work.
> > 
> > But we need a functional earlyprintk.  It has to be usable by simple 
> > _users_ who are not developers.  ARM is not going to remain this obscur 
> > embedded architecture forever.
> I repeat: that is not the point of DEBUG_LL.  DEBUG_LL is there for
> *developers* to debug their initial board bringup.  Nothing else.
> I repeat: I'm not going to have DEBUG_LL buggered up by do-gooders
> and people wanting BIOS shite and then have to re-invent it so that
> we can have decent debugging again.  That's NOT going to happen.  No
> way at all.
> > > > One could argue
> > > > that this option is for people who exactly know what they do only.
> > > 
> > > It _IS_ there for people who know what they're doing.  That's something
> > > I keep on saying about the LL debug stuff.  It's there to allow people
> > > to debug the early startup of the kernel.  It's not there for users.
> > 
> > That is not sufficient.
> Tough.  That's the way it is and it has to be lived with.  Early board
> bring up has absolutely nothing to do with users.  If users are doing
> early board bringup, they are kernel developers by definition.

So be it if you insist.  We'll then have to invent a better 
infrastructure in parallel to be able to do early enough serial output 
for users, both for earlyprintk and the zImage decompressor.


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