[PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and make it configurable

[Andrew Morton]

On Fri, 18 Dec 2015 13:11:41 +0100 Peter Zijlstra <peterz at infradead.org> wrote:

> On Fri, Dec 18, 2015 at 12:29:02PM +0100, Peter Zijlstra wrote:
> > On Fri, Dec 18, 2015 at 10:18:08AM +0000, Daniel Thompson wrote:
> > > I'm not entirely sure that this is an improvement.
> > 
> > What I do these days is delete everything in vprintk_emit() and simply
> > call early_printk().
> 
> On that, whoever made the device model use vprintk_emit() broke the
> debugger (KGDB/KDB) printk intercept, and the whole vprintk_func
> redirection scheme.

crap, we have a whole set of interfaces which are broken this way. 
printk_emit(), vprintk(), vprintk_emit().


commit 7ff9554bb578ba02166071d2d487b7fc7d860d62
Author:     Kay Sievers <kay at vrfy.org>
AuthorDate: Thu May 3 02:29:13 2012 +0200
Commit:     Greg Kroah-Hartman <gregkh at linuxfoundation.org>
CommitDate: Mon May 7 16:53:02 2012 -0700

    printk: convert byte-buffer to variable-length record buffer