linux-kernel - [PATCH] OLPC: only check for OFW signature on VSA-less Geodes

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Message-ID: <20080421170230.2db18632@ephemeral>
Date:	Mon, 21 Apr 2008 17:02:30 -0400
From:	Andres Salomon <dilinger@...ued.net>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	Mitch Bradley <wmb@...mworks.com>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joseph Fannin <jfannin@...il.com>,
	linux-kernel@...r.kernel.org, jordan.crouse@....com
Subject: [PATCH] OLPC: only check for OFW signature on VSA-less Geodes

On Mon, 21 Apr 2008 21:25:17 +0100
David Woodhouse <dwmw2@...radead.org> wrote:

> On Mon, 2008-04-21 at 15:46 -0400, Andres Salomon wrote:
> > Well, no, it wasn't already working; that's the reason this whole
> > thread started.  It was crashing someone's machine.  That's why the OFW
> > interface, as imperfect as it is, is an _improvement_.
> 
> You're proposing a new interface between bootloader and kernel as a
> temporary hack just to work around that until we fix it properly?
> 
> That seems like overkill to me. I'd just go for is_geode() as you
> suggested, and maybe PCI configuration tricks to detect the lack of VSA
> so we can be _fairly_ sure it's OLPC before we poke at it?
> 
> Or why not try '!page_is_ram(0xffffffc0 >> PAGE_SHIFT)' if it's just to
> avoid that particular warning? :)
> 


Okay, does anyone have a problem with this?

    




The OFW sig check requires an ioremap that is dangerous on non-OLPC
systems.  Long term, we should be getting the signature from the
device tree (/openprom/model), but for right now just limit the
check to only run on a subset of Geode (GX2/LX) systems.

Signed-off-by: Andres Salomon <dilinger@...ian.org>
---
 arch/x86/kernel/olpc.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/olpc.c b/arch/x86/kernel/olpc.c
index 11670be..3e66722 100644
--- a/arch/x86/kernel/olpc.c
+++ b/arch/x86/kernel/olpc.c
@@ -211,6 +211,10 @@ static int __init olpc_init(void)
 {
 	unsigned char *romsig;
 
+	/* The ioremap check is dangerous; limit what we run it on */
+	if (!is_geode() || geode_has_vsa2())
+		return 0;
+
 	spin_lock_init(&ec_lock);
 
 	romsig = ioremap(0xffffffc0, 16);
-- 
1.5.4.4


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