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[170.10.129.124]) by mx.google.com with ESMTPS id af79cd13be357-7c041ee5450si140044385a.608.2025.02.06.09.12.56 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2025 09:12:56 -0800 (PST) Received-SPF: pass (google.com: domain of berrange@redhat.com designates 170.10.129.124 as permitted sender) client-ip=170.10.129.124; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=K6p+S+nx; spf=pass (google.com: domain of berrange@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=berrange@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738861975; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=a9D14+ttmEpbIjxxs+8RIc6XcrX92xYxztdX0W95HbA=; b=K6p+S+nxed3dtBDDT2ryJo5qzHZqmGMOrgIW75HhWjej4YvXwVCMmdEV8pRBOBWL2SJsK+ e4wK39sOjM9zDyqc1n+u+iUqplZ6hznNh+qWFd/Om16hVYdIPKeI5UjYHn2NVQBzSTaAMm aDjx4WrKtR9x3mmkNe2ECALndkitlng= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-61-cxgIoaijOxOqJSkwXVbYJA-1; Thu, 06 Feb 2025 12:12:52 -0500 X-MC-Unique: cxgIoaijOxOqJSkwXVbYJA-1 X-Mimecast-MFC-AGG-ID: cxgIoaijOxOqJSkwXVbYJA Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 82551195604F; Thu, 6 Feb 2025 17:12:50 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.33]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C7D721800360; Thu, 6 Feb 2025 17:12:45 +0000 (UTC) Date: Thu, 6 Feb 2025 17:12:42 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Cc: qemu-devel@nongnu.org, qemu-arm@nongnu.org, Anton Johansson , Jason Wang , Paolo Bonzini , Alistair Francis , Thomas Huth , Richard Henderson , Peter Maydell , "Edgar E. Iglesias" , Markus Armbruster , Alex =?utf-8?Q?Benn=C3=A9e?= Subject: Re: [PATCH v5 11/16] hw/microblaze: Support various endianness for s3adsp1800 machines Message-ID: Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20250206131052.30207-1-philmd@linaro.org> <20250206131052.30207-12-philmd@linaro.org> <4624f149-76d0-4da5-8f13-8c015043c335@linaro.org> <3156dc3b-9553-4b5f-a934-f29ee0601887@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3156dc3b-9553-4b5f-a934-f29ee0601887@linaro.org> User-Agent: Mutt/2.2.13 (2024-03-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-TUID: 5A1Kn+QlHHzq On Thu, Feb 06, 2025 at 04:04:20PM +0100, Philippe Mathieu-Daudé wrote: > On 6/2/25 15:31, Daniel P. Berrangé wrote: > > On Thu, Feb 06, 2025 at 02:53:58PM +0100, Philippe Mathieu-Daudé wrote: > > > Hi Daniel, > > > > > > On 6/2/25 14:20, Daniel P. Berrangé wrote: > > > > On Thu, Feb 06, 2025 at 02:10:47PM +0100, Philippe Mathieu-Daudé wrote: > > > > > Introduce an abstract machine parent class which defines > > > > > the 'little_endian' property. Duplicate the current machine, > > > > > which endian is tied to the binary endianness, to one big > > > > > endian and a little endian machine; updating the machine > > > > > description. Keep the current default machine for each binary. > > > > > > > > > > 'petalogix-s3adsp1800' machine is aliased as: > > > > > - 'petalogix-s3adsp1800-be' on big-endian binary, > > > > > - 'petalogix-s3adsp1800-le' on little-endian one. > > > > > > > > Does it makes sense to expose these as different machine types ? > > > > > > > > If all the HW is identical in both cases, it feels like the > > > > endianness could just be a bool property of the machine type, > > > > rather than a new machine type. > > > > > > Our test suites expect "qemu-system-foo -M bar" to work out of > > > the box, we can not have non-default properties. > > > > > > (This is related to the raspberry pi discussion in > > > https://lore.kernel.org/qemu-devel/20250204002240.97830-1-philmd@linaro.org/). > > > > > > My plan is to deprecate 'petalogix-s3adsp1800', so once we > > > remove it we can merge both qemu-system-microblaze and > > > qemu-system-microblazeel into a single binary. > > > > > > If you don't want to add more machines, what should be the > > > endianness of the 'petalogix-s3adsp1800' machine in a binary > > > with no particular endianness? Either we add for explicit > > > endianness (fixing test suites) or we add one machine for > > > each endianness; I fail to see other options not too > > > confusing for our users. > > > > We would pick an arbitrary endianness of our choosing > > I guess. How does this work in physical machines ? Is > > the choice of endianess a firmware setting, or a choice > > by the vendor when manufacturing in some way ? > > Like MIPS*, SH4* and Xtensa*, it is a jumper on the board > (wired to a CPU pin which is sampled once at cold reset). That makes me thing even more it is just a machine type property. None the less, since you've already taken this pattern of dual machine types for BE & LE on MIPS/SH4/XTensa, I think we should stick with your precedent. Consistent modelling of endian handling across all machine types is most important IMHO With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|