From fnaumann@mail.cs.uni-magdeburg.de Fri Jul 9 00:18:26 2004 Message-ID: <1089324297.40edc509467aa@imp5-q.free.fr> Date: Fri, 9 Jul 2004 00:04:57 +0200 From: Xavier Joubert To: mint@fishpool.com Subject: Re: [MiNT] Trans.: Re: Questions about 68040 References: <1089262936.40ecd558ec19f@imp6-q.free.fr> <009001c464d7$f49a36b0$b80863d9@blaszak> <1089290023.40ed3f2735791@imp4-q.free.fr> <002701c4652c$648af050$480f63d9@blaszak> In-Reply-To: <002701c4652c$648af050$480f63d9@blaszak> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 User-Agent: Internet Messaging Program (IMP) 3.2.1 X-Virus-Scanned: by amavisd-new-20030616-p7 (Debian) at fishpool.fi Delivered-To: mint@fishpool.com Delivered-To: mint@lists.fishpool.fi X-ecartis-version: Ecartis v1.0.0 Sender: mint-bounce@lists.fishpool.fi Errors-to: mint-bounce@lists.fishpool.fi X-original-sender: xavier.joubert@free.fr Precedence: bulk List-help: List-unsubscribe: List-ID: X-List-ID: X-Milter: ClamAV 0.70/0.70kjel X-Milter: milter-regex 1.5jel X-Milter: ClamAV 0.70/0.70kjel X-Milter: milter-regex 1.5jel Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by prinz.cs.uni-magdeburg.de id i68MI7FH008873 Hi, Selon Konrad Kokoszkiewicz : > > This is a well known problem on Falcon/CT2 where user could > > access low mem in user mode. > Eh, what? So this must be protected by MMU in MiNT then. Didier Mequignon already worked on this. Basically CT2 boot code (We're talking about CT2 here - CT60 is far better on this topic) always use the PMMU to remap its TT-RAM from $0x04000000 to the well known 0x01000000. Didier wrote a small AUTO folder program which adds a supervisor protection on low mem. It's available on his web site (http://perso.wanadoo.fr/didierm , "download" page). This was later included into the CT2 boot code. Since the PMMU is used, MiNT was unable to run with memory protection. So Didier wrote a specific patch to allow MP with MiNT on CT2. It's commited to CVS in sys/arch/mprot030.c (search for "CT2" there). This code handle the strange TT-RAM base address, but it seems nothing was done to add supervisor protection of low mem. Anyway, it's not that easy. Reading the top of sys/arch/mprot030.c show us that MiNT uses 8K pages on 68 030. This means we can only protect 0x0000-0x1FFF at once. This is too much, since only 0x0000-0x07FF needs to be supervisor protected... We could find a way to do it nevertheless, but I don't think CT2 deserve so much efforts. Regards, Xavier