linux-kernel - Re: [BUGFIX]{PATCH] flush icache on ia64 take2

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Date:	Thu, 19 Jul 2007 22:32:08 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Zoltan.Menyhart@...l.net, linux-ia64@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	tony.luck@...el.com, nickpiggin@...oo.com.au, mike@...oyan.net,
	dmosberger@...il.com, y-goto@...fujitsu.com
Subject: Re: [BUGFIX]{PATCH] flush icache on ia64 take2

On Thu, 19 Jul 2007 22:01:18 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:

> On Thu, 19 Jul 2007 14:05:06 +0200
> Zoltan Menyhart <Zoltan.Menyhart@...l.net> wrote:
> 
> > KAMEZAWA Hiroyuki wrote:
> > 
> > > Then, what should I do more for fixing this SIGILL problem ?
> > > 
> > > -Kame
> > 
> > I can think of a relatively cheap solution:
> > 
> Maybe I should take performance numbers with the patch.
> 
> But is it too costly that flushing icache page only if a page is newly
> installed into the system (PG_arch1) && it is mapped as executable ?
> 
> I don't want to leak this (stupid) corner case to the file system layer.
> Hmm...can't we do clever flushing (like your idea) in VM layer ?
> 
A bit new idea.  How about this ?
==
- Set PG_arch_1 if  "icache is *not* coherent"
- make flush_dcache_page() to be empty func.
- For Montecito, add kmap_atomic(). This function just set PG_arch1.
  Then, "the page which is copied by the kernel" is marked as "not icache coherent page"
- icache_flush_page() just flushes a page which has PG_arch_1.
- Anonymous page is always has PG_arch_1. Tkae care of Copy-On-Write.
==

looks easy ?

-Kame

 
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