From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1uCEvG-0005yp-DJ for mharc-qemu-rust@gnu.org; Tue, 06 May 2025 05:49:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uCEvF-0005yU-OR for qemu-rust@nongnu.org; Tue, 06 May 2025 05:49:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uCEvD-0006Iu-Uh for qemu-rust@nongnu.org; Tue, 06 May 2025 05:49:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1746524946; 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:in-reply-to:in-reply-to: references:references; bh=j4zQy2jjm0EQeae9P6oM+RBC8ShtZDqZM+z3RBCYOxc=; b=XXSh23lhSwq1sp4kkiS8nBUdx7G4g0uB9S0iOeChsapJgOlYpfw6fyf4I2Dc/KN/OWRTuK Q8CbyM62nTgEIJ5Wv2oheztxqPGMzFekdpiDkVz5hr4LqbUVKFi9o96Bs/caV7aDjJS0rI Hn5Wj1LSEvBxeKc8ae01g/VzPK3qU3g= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-685-icjNE5uKOg6QIUrdinWgaA-1; Tue, 06 May 2025 05:49:05 -0400 X-MC-Unique: icjNE5uKOg6QIUrdinWgaA-1 X-Mimecast-MFC-AGG-ID: icjNE5uKOg6QIUrdinWgaA_1746524944 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1C6B11801A13; Tue, 6 May 2025 09:49:04 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.127]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 54EAD30001A2; Tue, 6 May 2025 09:49:02 +0000 (UTC) Date: Tue, 6 May 2025 10:48:59 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Zhao Liu Cc: Paolo Bonzini , qemu-devel@nongnu.org, qemu-rust@nongnu.org Subject: Re: [PATCH preview 0/5] rust: allow minimum version of 1.83 Message-ID: Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20250505100854.73936-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.414, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-rust@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: QEMU Rust-related patches and discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 06 May 2025 09:49:10 -0000 On Tue, May 06, 2025 at 05:26:12PM +0800, Zhao Liu wrote: > > > "enable Rust" supports v1.77 and "enable all devices written in Rust" > > > supports v1.83, correct? > > > > Both support v1.83 only. However, if Rust is missing or old, "enable > > all devices written in Rust" will fail compilation (e.g. Kconfig would > > fail for ARM/x86 targets due to unsatisfiable CONFIG_PL011); > > In this case, a brand new Rust device (without a corresponding C > version) would be unable to compile on the above platforms which don't > support v1.83. I'm not sure if this is an acceptable limitation or > policy. (Has there been a similar case in history?) > > > "enable Rust" will simply pick the C version of the PL011 and HPET devices. > > I support this, at least the compatibility with the old QEMU won't be > broken! Then all C devices rewritten in Rust can be covered by this > category. I don't really like this because it perpetuates a state where we have parallel implementations of devices that have to be kept in sync. If we're re-writing C devices in Rust, we need to be able to promptly drop the C impl once the Rust impl is feature complete. Keeping 2 impls is a general maint burden, as well as an ongoing vmstate compatibility danger if a change in one impl is not matched by an identical change in the other impl. IMHO having Rust declared supported in QEMU should be aligned with being able to drop C impls of any ported devices. 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 :|