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Tue, 19 May 2020 05:35:44 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id BBC6211358BC; Tue, 19 May 2020 07:35:42 +0200 (CEST) From: Markus Armbruster To: Joel Stanley Subject: Re: [PATCH 04/24] aspeed: Don't create unwanted "ftgmac100", "aspeed-mmi" devices References: <20200518050408.4579-1-armbru@redhat.com> <20200518050408.4579-5-armbru@redhat.com> <9fc4a6e2-fa90-ba62-91cf-e22eb3ef4cdc@kaod.org> Date: Tue, 19 May 2020 07:35:42 +0200 In-Reply-To: (Joel Stanley's message of "Tue, 19 May 2020 00:38:51 +0000") Message-ID: <87zha45vwx.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=207.211.31.120; envelope-from=armbru@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/19 00:34:39 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: Peter Maydell , berrange@redhat.com, Eduardo Habkost , Andrew Jeffery , QEMU Developers , qemu-arm , =?utf-8?Q?C=C3=A9dric?= Le Goater , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Joel Stanley writes: > On Mon, 18 May 2020 at 12:19, C=C3=A9dric Le Goater wrote: >> >> On 5/18/20 7:03 AM, Markus Armbruster wrote: >> > These devices are optional, and controlled by @nb_nics. >> > aspeed_soc_ast2600_init() and aspeed_soc_init() create the maximum >> > supported number. aspeed_soc_ast2600_realize() and >> > aspeed_soc_realize() realize only the wanted number. Works, although >> > it can leave unrealized devices hanging around in the QOM composition >> > tree. Affects machines ast2500-evb, ast2600-evb, palmetto-bmc, >> > romulus-bmc, swift-bmc, tacoma-bmc, and witherspoon-bmc. >> > >> > Make the init functions create only the wanted ones. Visible in "info >> > qom-tree"; here's the change for ast2600-evb: >> > >> > /machine (ast2600-evb-machine) >> > [...] >> > /soc (ast2600-a1) >> > [...] >> > /ftgmac100[0] (ftgmac100) >> > /ftgmac100[0] (qemu:memory-region) >> > - /ftgmac100[1] (ftgmac100) >> > - /ftgmac100[2] (ftgmac100) >> > - /ftgmac100[3] (ftgmac100) >> > /gpio (aspeed.gpio-ast2600) >> > [...] >> > /mii[0] (aspeed-mmi) >> > /aspeed-mmi[0] (qemu:memory-region) >> > - /mii[1] (aspeed-mmi) >> > - /mii[2] (aspeed-mmi) >> > - /mii[3] (aspeed-mmi) >> > /rtc (aspeed.rtc) >> > >> > I'm not sure creating @nb_nics devices makes sense. How many does the >> > physical chip provide? >> >> The AST2400, AST2500 SoC have 2 macs and the AST2600 has 4. Each machine >> define the one it uses, generally MAC0 but the tacoma board uses MAC3. >> >> Shouldn't the model reflect the real address space independently from >> the NIC backends defined on the command line ? > > Agreed, the MAC hardware is present in all instances of the AST2600, > so they should be present in qemu. Only some boards wire up a network > device to the other side. I guess an unwired NIC behaves as if no cable was plugged into the external connector ("no carrier"). We can model that. > It would be advantageous for us to be able to specify which device is > being connected to on the command line. Currently we do this by > connecting all devices up to the one we care about which is an ugly > workaround. We use -nic to configure onboard NICs. The configuration gets deposited in nd_table[] for board code to pick up. Boards use nd_table[0] for their first NIC, nd_table[1] for the second, and so forth. How they order their NICs is part of their stable user interface. To leave a NIC unplugged, use -nice none. Example: -nic none -nic user leaves the first NIC unplugged, and plugs the second one using a user network backend. Say the board contains a SoC that provides four NICs, but the board wires up only the last one. Then board code should use nd_table[0] for that last one. I don't remember whether network device frontends can work without a backend, or need a null backend. If the latter, then board code needs to supply such null backends. >> How should we proceed in such cases ? Model the physical hardware as faithfully as we can. Follow-up patches welcome!