From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4DF0ACAC5BB for ; Fri, 10 Oct 2025 09:14:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v79B5-0004ar-Ku; Fri, 10 Oct 2025 05:12:43 -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 1v79Ay-0004aW-CQ for qemu-devel@nongnu.org; Fri, 10 Oct 2025 05:12:37 -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 1v79Ap-0001qH-4m for qemu-devel@nongnu.org; Fri, 10 Oct 2025 05:12:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760087542; 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=q297XgE77C7e3jjgsaRkPx7hUirYtDhuGyjKQOJuI9U=; b=I4UbMmID4sKmiM+3FtNDiZj5m0JpuIdUTuXkfAypHOf4FavSFGtB1bxhTfLocVgVSR0IZy rqWDdfZRa+bP6msM9Z1mv4FN23MfiAfb85SE4PS/HUSYaFaicDmbvJu8ppaLKMd7O9oss3 yj8His8Lcna52M4oeJ24fX0wAzU5RHU= Received: from mx-prod-mc-06.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-295-cWaPf3HeP1GcLFP5Hhewbg-1; Fri, 10 Oct 2025 05:12:16 -0400 X-MC-Unique: cWaPf3HeP1GcLFP5Hhewbg-1 X-Mimecast-MFC-AGG-ID: cWaPf3HeP1GcLFP5Hhewbg_1760087535 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 99630180057B; Fri, 10 Oct 2025 09:12:14 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.177]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9965930001B7; Fri, 10 Oct 2025 09:12:08 +0000 (UTC) Date: Fri, 10 Oct 2025 10:12:05 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Gerd Hoffmann Cc: qemu-devel@nongnu.org, Paolo Bonzini , Yanan Wang , Markus Armbruster , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Fabiano Rosas , Eric Blake , "Dr. David Alan Gilbert" , Laurent Vivier , Marcel Apfelbaum , Zhao Liu , Eduardo Habkost Subject: Re: [PATCH v3] hw/uefi: add "info firmware-log" + "query-firmware-log" monitor commands Message-ID: References: <20251010071008.2555267-1-kraxel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251010071008.2555267-1-kraxel@redhat.com> 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, 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, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_PASS=-0.001, T_SPF_HELO_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Oct 10, 2025 at 09:10:08AM +0200, Gerd Hoffmann wrote: > Starting with the edk2-stable202508 tag OVMF (and ArmVirt too) have > optional support for logging to a memory buffer. There is guest side > support -- for example in linux kernels v6.17+ -- to read that buffer. > But that might not helpful if your guest stops booting early enough that > guest tooling can not be used yet. So host side support to read that > log buffer is a useful thing to have. > > This patch implements both qmp and hmp monitor commands to read the > firmware log. > > Signed-off-by: Gerd Hoffmann > --- > include/monitor/hmp.h | 1 + > hw/uefi/ovmf-log.c | 265 +++++++++++++++++++++++++++++++++++++ > tests/qtest/qmp-cmd-test.c | 2 + > hmp-commands-info.hx | 14 ++ > hw/uefi/meson.build | 2 +- > qapi/machine.json | 23 ++++ > 6 files changed, 306 insertions(+), 1 deletion(-) > create mode 100644 hw/uefi/ovmf-log.c > diff --git a/hw/uefi/ovmf-log.c b/hw/uefi/ovmf-log.c > new file mode 100644 > index 000000000000..89e27d916531 > --- /dev/null > +++ b/hw/uefi/ovmf-log.c > @@ -0,0 +1,265 @@ > +static void handle_ovmf_log_range(GString *out, > + dma_addr_t start, > + dma_addr_t end, > + Error **errp) > +{ > + g_autofree char *buf = NULL; > + > + if (start > end) { > + return; > + } > + > + buf = g_malloc(end - start + 1); > + if (dma_memory_read(&address_space_memory, start, > + buf, end - start, > + MEMTXATTRS_UNSPECIFIED)) { > + error_setg(errp, "firmware log: buffer read error"); > + return; > + } > + > + buf[end - start] = 0; > + g_string_append_printf(out, "%s", buf); How about eliminating the intermediate buffer alloocation / printf by reading straight into the GString buf ? Something like size_t len = end - start; g_string_set_size(out, out->len + len); if (dma_memory_read(&address_space_memory, start, out->str + (out->len - len), len, MEMTXATTRS_UNSPECIFIED)) { ... } 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 :|