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Fri, 26 Nov 2021 12:13:53 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B3E17AC062; Fri, 26 Nov 2021 12:13:52 +0000 (GMT) Received: from localhost (unknown [9.211.89.149]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTPS; Fri, 26 Nov 2021 12:13:52 +0000 (GMT) From: Fabiano Rosas To: Segher Boessenkool , =?utf-8?Q?C=C3=A9dric?= Le Goater Subject: Re: [OpenBIOS] Re: [RFC PATCH 0/2] QEMU/openbios: PPC Software TLB support in the G4 family In-Reply-To: <20211126103732.GP614@gate.crashing.org> References: <20211119134431.406753-1-farosas@linux.ibm.com> <87pmqpqknn.fsf@linux.ibm.com> <48c4262-ff7d-2897-9764-cadd98683e97@eik.bme.hu> <20211125093801.GM614@gate.crashing.org> <484dc989-71db-6273-e868-efaf2ad29fcf@kaod.org> <20211126103732.GP614@gate.crashing.org> Date: Fri, 26 Nov 2021 09:13:49 -0300 Message-ID: <87lf1bqflu.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: yFv838ZyEmu5RizGuFqO_M9y_GwP4Jv6 X-Proofpoint-ORIG-GUID: mGDNKi5uGhOWSIp8ZDzLbaF519dm1BJx X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-26_03,2021-11-25_02,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 bulkscore=0 mlxscore=0 phishscore=0 spamscore=0 adultscore=0 lowpriorityscore=0 mlxlogscore=860 malwarescore=0 priorityscore=1501 clxscore=1011 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111260071 Received-SPF: pass client-ip=148.163.156.1; envelope-from=farosas@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: danielhb413@gmail.com, qemu-devel@nongnu.org, qemu-ppc@nongnu.org, openbios@openbios.org, david@gibson.dropbear.id.au Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Segher Boessenkool writes: > Hi! > > On Fri, Nov 26, 2021 at 09:34:44AM +0100, C=C3=A9dric Le Goater wrote: >> On 11/25/21 10:38, Segher Boessenkool wrote: >> >On Thu, Nov 25, 2021 at 01:45:00AM +0100, BALATON Zoltan wrote: >> >>As for guests, those running on the said PowerMac G4 should have suppo= rt >> >>for these CPUs so maybe you can try some Mac OS X versions (or maybe >> > >> >OSX uses hardware pagetables. >> > >> >>MorphOS but that is not the best for debugging as there's no source >> >>available nor any help from its owners but just to see if it boots it = may >> >>be sufficient, it should work on real PowerMac G4). >> > >> >I have no idea what MorphOS uses, but I bet HPT as well. That is >> >because HPT is fastest in general. Software TLB reloads are good in >> >special cases only; the most common is real-time OSes, which can use its >> >lower guaranteed latency for some special address spaces (and can have a >> >simpler address map in general). >>=20 >> The support was added to QEMU knowing that Linux didn't handle soft TLBs. >> And the commit says that it was kept disabled initially. I guess that was >> broken these last years. > > Ah :-) So when was it enabled, do you know? Hm.. That commit message does not match the code. They simply added the software TLB implementation to an already existing SOFT_74xx MMU model. I don't see anything that would keep it disabled at that time.