From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 758A22848A7 for ; Thu, 26 Mar 2026 13:01:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774530085; cv=none; b=Z9TjYUQv0FH/WeKBaHmvEclQ51vo32h60+a8YIWC7fFDTn1uoRKLOSVpTnXkyhnb7Ok4WiOUhYfCigLTk8WXgpuSzUPPgKlDDpYCyY2B+HZO5HyCDIWo6HoPCEk5zRNPywWhrfl75+Jflc3mCm6WxZSUl2d9Xr2oFEpubZvHjPU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774530085; c=relaxed/simple; bh=JtfRI+SGda94ltJQL8u/sOjJTSX26NJ6vN3Uql6fp98=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=YsCFGYSf0zmxc8mIMmUWVnTnZfUlIkCq/1SImSaB+KddX6qSRd3Afz+Zzw2YCNp+HcfcQ8EhjfhsE0trE50iiV1STLO3w0FltTZMOhmzbbiXzhsZLAVsgDNFYO6h8xU4AmmY4Qse69/2QDkYf5VhxyezL6cPZbPE+tHPJQSzYF4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=GY+2M+Rp; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GY+2M+Rp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1774530082; h=from:from: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=dgqnh8YCVC64TnA3VJFCquY3LHbWRG2/wHmvHeqgzDw=; b=GY+2M+RptLCcfW6nYQGPNPs6J5WUa0uNqKDh+50rdiJW4HX2kw6Y6wr940JLC9bLVo/+jK U6p3TjjguC1NAIzoIya+p09fEwYdjTPECe34bshRqIDb/RS+7+/IEdJ6ILuELznwpCqw1O eintz1vESrTBSIx5xrRSZx6rLf3JOT4= 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-235-dkj09fOLMO2CHio9kGdSLw-1; Thu, 26 Mar 2026 09:01:19 -0400 X-MC-Unique: dkj09fOLMO2CHio9kGdSLw-1 X-Mimecast-MFC-AGG-ID: dkj09fOLMO2CHio9kGdSLw_1774530071 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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5F0EF1955F18; Thu, 26 Mar 2026 13:01:10 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.6]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 627103000223; Thu, 26 Mar 2026 13:01:09 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 0600221E6937; Thu, 26 Mar 2026 14:01:07 +0100 (CET) From: Markus Armbruster To: Alireza Sanaee Cc: , , , , , , , , , , , , Subject: Re: [PATCH 1/9] hw/mem: Add tag support to generic host memory backends In-Reply-To: <20260326112921.000028e6.alireza.sanaee@huawei.com> (Alireza Sanaee's message of "Thu, 26 Mar 2026 11:29:21 +0000") References: <20260325184259.366-1-alireza.sanaee@huawei.com> <20260325184259.366-2-alireza.sanaee@huawei.com> <87a4vuhnxy.fsf@pond.sub.org> <20260326112921.000028e6.alireza.sanaee@huawei.com> Date: Thu, 26 Mar 2026 14:01:06 +0100 Message-ID: <87bjgag2y5.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: HEdkgNvOuX1cHxpYiHPfMYvl5-JMNJJM5M3AlwP7Fxo_1774530071 X-Mimecast-Originator: redhat.com Content-Type: text/plain Alireza Sanaee writes: > On Thu, 26 Mar 2026 11:42:17 +0100 > Markus Armbruster wrote: > > Hi Markus, > >> Alireza Sanaee writes: >> >> > Add a string tag property to HostMemoryBackend so that backends can be >> > identified by a user-assigned name at runtime. Expose the property through >> > QOM and add a host_memory_backend_find_by_tag() helper that walks the >> > object tree to locate a backend by its tag. >> >> Why can't you use the QOM ID? >> >> $ qemu-system-x86_64 -S -display none -monitor stdio -object memory-backend-ram,id=fred,size=1M >> QEMU 10.2.90 monitor - type 'help' for more information >> (qemu) info qom-tree /objects/fred >> /fred (memory-backend-ram) >> /fred[0] (memory-region) >> >> > > Fair question. The ID would have been a solution if it had accepted GUIDs. CXL spec > requires GUIDs for extents as identification, hence new tag property. Your commit message should state that this needs to be a GUID and why. > alireza@blue-ocean:~/Downloads$ qemu-system-x86_64 -s -display none -monitor std > io -object memory-backend-ram,id=02bb2436-e87d-4aa1-b2be-aaffdd76bb79,size=1M > qemu-system-x86_64: -object memory-backend-ram,id=02bb2436-e87d-4aa1-b2be-aaffdd > 76bb79,size=1M: Parameter 'id' expects an identifier > Identifiers consist of letters, digits, '-', '.', '_', starting with a letter. > > Thanks, > Ali