From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by mx.groups.io with SMTP id smtpd.web11.5637.1681991179117645022 for ; Thu, 20 Apr 2023 04:46:19 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=e6p2pEk3; spf=pass (domain: redhat.com, ip: 170.10.133.124, mailfrom: kraxel@redhat.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681991178; 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=kosRCMzLi0bM6rWedtQCTnV4culGoPwpMIo28l+VAWk=; b=e6p2pEk3ZA5lrKPjvqfn7iHVSc+XuAJQNLs634gYcWhnegSNd9IYpbJhA7cAX9Vn2H4ELQ E/xPXTFg4JwVg8NLN8507wxzA/IXsg1CQfPNnkJ3TGu9Z1FJe6PJOgnxpUhSF2CTC0L35N jz9KbuzsY3oHylggFyfaW2Dn7GF2EW0= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-490-YZftkyPZMjSkrW1jGIRLjA-1; Thu, 20 Apr 2023 07:46:13 -0400 X-MC-Unique: YZftkyPZMjSkrW1jGIRLjA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 809CE1C0897D; Thu, 20 Apr 2023 11:46:12 +0000 (UTC) Received: from sirius.home.kraxel.org (unknown [10.39.192.59]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EF3121410F1C; Thu, 20 Apr 2023 11:46:11 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id C826D1804A48; Thu, 20 Apr 2023 13:46:10 +0200 (CEST) Date: Thu, 20 Apr 2023 13:46:10 +0200 From: "Gerd Hoffmann" To: "Gupta, Pankaj" Cc: devel@edk2.groups.io, Ard Biesheuvel , Stefan Berger , Julien Grall , Anthony Perard , Ard Biesheuvel , Jordan Justen , Pawel Polawski , Oliver Steffen , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Jiewen Yao Subject: Re: [edk2-devel] [PATCH 0/4] OvmfPkg: add virtio serial driver Message-ID: References: <20230417090320.225046-1-kraxel@redhat.com> <75755155-c93a-bc72-5ef7-58ad1a9c9a73@amd.com> MIME-Version: 1.0 In-Reply-To: <75755155-c93a-bc72-5ef7-58ad1a9c9a73@amd.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi, > > libvirt snippet (add to ): > > > > > > > > > Was thinking about the motivation to add the virtio serial device. > > AFAIU this can provide a console in bios/early boot based on "virtio". > Currently we can only get it with emulated PTY device which is slow > because of frequent VMEXITS because of ioport write? Yes, it has better performance because it wouldn't vmexit for every single character. Dawback is that it wouldn't work for early logging, the driver loads relatively late because it depends on pci and virtio. So if the firmware panics in SEC or PEI you wouldn't see that. So for debug logging it isn't the best choice, for efi shell and grub it works fine. > Or is there any other reason (e.g across the ARCH support) to add this > support in UEFI ? Should work on all architectures, although it needs some platform setup code to have the firmware actually bind the firmware console to it (see patch #4). Another nice property of a virtio console is that systemd will spawn a getty there even if it is not explicitly configured as console device. take care, Gerd