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That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Michael S. Tsirkin" , Jason Wang , Mark Cave-Ayland , QEMU Developers , Peter Xu , Gerd Hoffmann , "Edgar E. Iglesias" , Eduardo Habkost , "Edgar E . Iglesias" , Qemu-block , Li Qiang , "Emilio G . Cota" , Joel Stanley , David Gibson , Laszlo Ersek , Robert Foley , Alistair Francis , Richard Henderson , Beniamino Galvani , Eric Auger , qemu-arm , Peter Chubb , =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , Stefan Hajnoczi , Paolo Bonzini , Richard Henderson , Tony Nguyen , Prasad J Pandit , Alexander Bulekov , Andrew Jeffery , =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= , Emanuele Giuseppe Esposito , =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= , Andrew Baumann , qemu-ppc , Klaus Jensen , Jan Kiszka Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 9 Sep 2020 at 10:12, Stefan Hajnoczi wrote: > > On Thu, Sep 03, 2020 at 01:08:19PM +0200, Philippe Mathieu-Daud=C3=A9 wro= te: > > The main patch is: > > "exec/memattrs: Introduce MemTxAttrs::direct_access field". > > This way we can restrict accesses to ROM/RAM by setting the > > 'direct_access' field. Illegal accesses return MEMTX_BUS_ERROR. > > QEMU needs to simulate the behavior of real hardware. What is the > behavior of real hardware? It varies, depending on the hardware. The most common thing is probably "happens to work by luck", which is OK for hardware but doesn't help us much since our software implementation is naturally more serialized than hardware is and since we don't want to allow guests to make QEMU crash or misbehave. thanks -- PMM