From nobody Fri Oct 23 21:31:51 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1792564300; cv=none; d=zohomail.com; s=zohoarc; b=GZIs3zqmLXIHArCCAyl+bqB2QJVQhcUNguWafg2CrO88iUqw35Lo+Kz4w3VLvg4JuFQ0/v/PFyZBmxpgj+04ct3FfAQ0eIxV/g6b/GJKoB+WDJxeaUvkTE/yu8WAg4Tb7Zgluu4mUABd1OxZJg4t+G6SDJzd/EQU9daXsH9aryA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1792564300; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=66jF8UazuBg/7lKHQxDgOXrP/gAMJa3ieQpV/jwxNao=; b=WqjyYidUypbKeXUP4b755C1yG52ucL2y7WAOmcpPm3IUKZPnhM9nDA3KZhkvecwXmSGVJvlwCRcXNt3ju77zUmJEEN8bQIUfXuCuQMKKaKJ5CXO4qvz92QQKrZko/clO8eBVkFqzqJGrpx45wZ0kQ6xrkm2+R9pF99deUtr0fsc= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1792564300735434.0722444812641; Tue, 20 Oct 2026 23:31:40 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xJPrA-0004rS-7G; Wed, 21 Oct 2026 02:31:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xJPr0-0004r9-Kp for qemu-devel@nongnu.org; Wed, 21 Oct 2026 02:31:16 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xJPqx-0004Q9-BV for qemu-devel@nongnu.org; Wed, 21 Oct 2026 02:31:13 -0400 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-692-hc3sYvjpMGWqNf05lVobRA-1; Wed, 21 Oct 2026 06:31:08 +0000 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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 65A07180075A; Wed, 21 Oct 2026 06:31:07 +0000 (UTC) Received: from sirius.home.kraxel.org (unknown [10.44.48.54]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9DD6A1800495; Wed, 21 Oct 2026 06:31:06 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 7EB421800782; Wed, 21 Oct 2026 08:31:05 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1792564269; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=66jF8UazuBg/7lKHQxDgOXrP/gAMJa3ieQpV/jwxNao=; b=Yc8ybhephtKl1F2aYiuMIuntdV6JjsgB38uCc9t06k85iQIJeF/3fx6AZdosOcRumlvj9s fIIrUhDAMmaIjjVIm1dOP4ndIp1wINIa/XwS4a18UJXaswFz2HutiVaAPYsAjqEmX2yBhc RZ6sOiYDO6ghDxBE7GZhVuj0Xwpj3IM= X-MC-Unique: hc3sYvjpMGWqNf05lVobRA-1 X-Mimecast-MFC-AGG-ID: hc3sYvjpMGWqNf05lVobRA_1792564267 From: Gerd Hoffmann To: qemu-devel@nongnu.org Cc: "Michael S. Tsirkin" , Paolo Bonzini , Richard Henderson , Gerd Hoffmann , John Snow Subject: [PATCH] x86: mmap kernel for direct kernel boot Date: Wed, 21 Oct 2026 08:31:05 +0200 Message-ID: <20261021063105.102520-1-kraxel@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=kraxel@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.329, 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, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 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: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1792564302805158500 Content-Type: text/plain; charset="utf-8" Reduce memory footprint by mapping the kernel into memory instead of reading into allocated memory in the common case (no -dtb $file on the qemu command line). Cc: John Snow Signed-off-by: Gerd Hoffmann Tested-by: John Snow --- hw/i386/x86-common.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/hw/i386/x86-common.c b/hw/i386/x86-common.c index fa18bf1aeceb..25e141aa8537 100644 --- a/hw/i386/x86-common.c +++ b/hw/i386/x86-common.c @@ -911,16 +911,31 @@ void x86_load_linux(X86MachineState *x86ms, } =20 setup =3D g_malloc(setup_size); - kernel =3D g_malloc(kernel_size); fseek(f, 0, SEEK_SET); if (fread(setup, 1, setup_size, f) !=3D setup_size) { fprintf(stderr, "fread() failed\n"); exit(1); } - fseek(f, 0, SEEK_SET); - if (fread(kernel, 1, kernel_size, f) !=3D kernel_size) { - fprintf(stderr, "fread() failed\n"); - exit(1); + if (dtb_filename) { + /* read kernel into allocated memory, so we can realloc for the dt= b */ + kernel =3D g_malloc(kernel_size); + fseek(f, 0, SEEK_SET); + if (fread(kernel, 1, kernel_size, f) !=3D kernel_size) { + fprintf(stderr, "fread() failed\n"); + exit(1); + } + } else { + /* mmap kernel */ + GMappedFile *mapped_file; + GError *gerr =3D NULL; + + mapped_file =3D g_mapped_file_new(kernel_filename, false, &gerr); + if (!mapped_file) { + fprintf(stderr, "qemu: error reading kernel %s: %s\n", + kernel_filename, gerr->message); + exit(1); + } + kernel =3D (uint8_t *)g_mapped_file_get_contents(mapped_file); } fclose(f); =20 --=20 2.56.0