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[82.11.186.48]) by smtp.gmail.com with ESMTPSA id n32sm3374467wms.42.2021.11.11.10.21.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Nov 2021 10:21:50 -0800 (PST) Date: Thu, 11 Nov 2021 18:21:48 +0000 From: Leif Lindholm To: Peter Maydell Subject: Re: [PATCH v8 07/10] hw/arm/sbsa-ref: add ITS support in SBSA GIC Message-ID: References: <20210812165341.40784-8-shashi.mallela@linaro.org> <20210902124258.mqjhx7lqqvkczf6a@leviathan> <20211015122351.vc55mwzjbevl6wjy@leviathan> <20211109204249.usvfatm3frar3u7a@leviathan> <20211109225251.gfr2mvm3jynvdsnk@leviathan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Host-Lookup-Failed: Reverse DNS lookup failed for 2a00:1450:4864:20::434 (failed) Received-SPF: pass client-ip=2a00:1450:4864:20::434; envelope-from=leif@nuviainc.com; helo=mail-wr1-x434.google.com X-Spam_score_int: -10 X-Spam_score: -1.1 X-Spam_bar: - X-Spam_report: (-1.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, PDS_HP_HELO_NORDNS=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no 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: Marcin Juszkiewicz , "Michael S. Tsirkin" , Shashi Mallela , Radoslaw Biernacki , QEMU Developers , narmstrong@baylibre.com, Eric Auger , qemu-arm , Igor Mammedov , Alex =?iso-8859-1?Q?Benn=E9e?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Nov 11, 2021 at 16:55:09 +0000, Peter Maydell wrote: > On Tue, 9 Nov 2021 at 22:52, Leif Lindholm wrote: > > > > On Tue, Nov 09, 2021 at 21:21:46 +0000, Peter Maydell wrote: > > > The other thing we should nail down is how the user is going to > > > select which flavour of machine they want to provide. Three > > > options: > > > (1) no control, QEMU just emulates whatever the newest flavour is. > > > User needs to go find a firmware image new enough to cope. > > > (2) different flavours exposed as different machine types > > > (analogous to how we have musca-a and musca-b1, or raspi3ap and > > > raspi3b, for instance). Old user command lines keep working > > > because -M sbsa-ref doesn't change; the new stuff would be > > > available via -M sbsa-ref-2 or whatever. > > > (3) different flavours exposed via a property > > > (so you would have -M sbsa-ref,machine-revision=2 or something). > > > If the revision defaults to 1 then old user setups still work > > > but everybody starts to have to cart around an extra command > > > line argument. If it defaults to "newest we know about" you > > > get the opposite set of tradeoffs. > > > > I'm leaning towards (1), at least while working towards a "complete" > > platform (when we may still add/change features, but not how those > > features are communicated to the firmware). > > That's certainly the easiest on the QEMU side; you know the > userbase so would know whether that kind of compat break is > going to be OK with them. > > Q1: who is going to write the code for this? Me, my team, and perhaps a little bit of help from Shashi where it intersects his code. > Q2: do we want to try to land "ITS in sbsa-ref" in 6.2? Given > we're in freeze we're quite short of time even if we handwave > the fact it's a new feature, not a bugfix, so I would lean > towards 'no'... Shashi - what is your feeling? If we could make ITS support depend on the platform version being communicated through TF-A, we could simplify the transition a lot. But that would definitely mean missing 6.2. Peter - could we sneak in an "add version node to DT" into 6.2? / Leif