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From: "Matt Sealey" <matt@genesi-usa.com>
To: "'Paul Mackerras'" <paulus@samba.org>,
	"'Albert Cahalan'" <acahalan@gmail.com>
Cc: linuxppc-dev@ozlabs.org, debian-powerpc@lists.debian.org
Subject: RE: PowerPC paxtest results w/ gcc-4.1
Date: Mon, 14 Aug 2006 13:50:53 +0200	[thread overview]
Message-ID: <000301c6bf97$e9151e00$99dfdfdf@bakuhatsu.net> (raw)
In-Reply-To: <17630.27174.711916.643790@cargo.ozlabs.ibm.com>



> Of course, that won't make all that much difference on your 
> Cube, because the G4 CPU doesn't have hardware support for 
> non-executable pages (any readable page is executable)

I don't think this is true?

Book I compatible PowerPC's have had a "no-executable" bit in
the page protection flags since the dark ages.. see page 7-38
and 7-39 of the 'Programming Environments Manual for 32-Bit
Microprocessors'.. this document predates even the G3.

As far as the documentation goes, you can make the page
readable and writable to the LSU, but the N bit causes the
instruction fetch to cause a machine check. That's pretty
"not-executable" to me at least :)

-- 
Matt Sealey <matt@genesi-usa.com>
Manager, Genesi, Developer Relations

  parent reply	other threads:[~2006-08-14 11:51 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-12  5:50 PowerPC paxtest results w/ gcc-4.1 Albert Cahalan
2006-08-12 11:35 ` Paul Mackerras
2006-08-12 14:36   ` Albert Cahalan
2006-08-12 23:54     ` Paul Mackerras
2006-08-13  2:48       ` Albert Cahalan
2006-08-13  3:23         ` Paul Mackerras
2006-08-13  4:11           ` Albert Cahalan
2006-08-13 16:45             ` Hollis Blanchard
2006-08-13 18:59               ` Albert Cahalan
2006-08-14 12:17             ` Matt Sealey
2006-08-14 14:20               ` Kumar Gala
2006-08-13  3:29       ` Alan Modra
2006-08-13 18:56       ` Albert Cahalan
2006-08-14 11:50       ` Matt Sealey [this message]
2006-08-15  3:59         ` Paul Mackerras
2006-08-16 10:59           ` Gabriel Paubert
2006-08-16 11:07             ` Paul Mackerras
2006-08-16 14:43               ` Albert Cahalan
2006-08-16 17:49             ` Segher Boessenkool

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