[lkml]   [2007]   [Sep]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch 3/8] Immediate Values - Kconfig menu in EMBEDDED
On Fri, Sep 07, 2007 at 08:46:48AM -0400, Mathieu Desnoyers wrote:
> * Andi Kleen ( wrote:
> > > +config IMMEDIATE
> > > + default y if !DISABLE_IMMEDIATE
> >
> > It's still unclear to me why DISABLE_IMMEDIATE is needed. It would
> > be better to make it just the default.
> >
> It is actually the default on any non embedded configuration. Do you
> think we should make it default to on on embedded configs too ?

I would prefer to not have any config options at all and let
the non converted architectures always use a asm-generic fallback.

> The idea here is to give embedded system developers incentives to
> create an optimized immediate value header for their architecture. I

Sounds like a quite bogus way to do this.

> fear that if it is not trivial to disable when they need to use ROM to
> put the kernel code (as kprobes is, meaning, with a single config
> option), they will refuse to event think about including an optimized
> immediate value header for their architecture.

#include <asm-generic/generic-immediate.h>
/* optimized implementation */

That's trivial.

> And yes, having a CONFIG_READ_ONLY_TEXT makes sense, but it implies
> menu dependencies with not only immediate values but also kprobes,
> paravirt, alternatives, (am I missing others ?)

paravirt and alternatives are x86 only.

I don't think CONFIG_READ_ONLY_TEXT on x86 makes sense.

On other architectures they have to deal with kprobes, but they
presumably do this already. Not really your problem I suspect.

> As long as we find a way for people to disable _all_ code patching in
> their kernel, I'm happy with that. But since every existing code
> patching mechanism can currently be disabled one by one, it makes sense
> to do the same for the immediate values. Having a global
> CONFIG_READ_ONLY_TEXT should IMHO come in a separate effort.

You're clearly deep into overdesign territory here.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-09-08 00:43    [W:0.077 / U:4.972 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site