{"id":2219344,"url":"http://patchwork.ozlabs.org/api/1.0/patches/2219344/?format=json","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/1.0/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260402215629.745866-22-ruslichenko.r@gmail.com>","date":"2026-04-02T21:56:06","name":"[v3,21/33] hw/arm/arm_generic_fdt: Add support for host-backed RAM regions","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"756c7b046e2e03a99a0ddc01f42f1f6649482157","submitter":{"id":92275,"url":"http://patchwork.ozlabs.org/api/1.0/people/92275/?format=json","name":"Ruslan Ruslichenko","email":"ruslichenko.r@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260402215629.745866-22-ruslichenko.r@gmail.com/mbox/","series":[{"id":498555,"url":"http://patchwork.ozlabs.org/api/1.0/series/498555/?format=json","date":"2026-04-02T21:55:47","name":"hw/arm: Introduce generic FDT-driven machine","version":3,"mbox":"http://patchwork.ozlabs.org/series/498555/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2219344/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=N3lcUhX3;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)"],"Received":["from lists.gnu.org (lists.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fmwj80yrTz1yD3\n\tfor ; Fri, 03 Apr 2026 08:58:36 +1100 (AEDT)","from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1w8Q2k-0000GD-K0; Thu, 02 Apr 2026 17:57:39 -0400","from eggs.gnu.org ([2001:470:142:3::10])\n by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1w8Q2W-00005L-Pe\n for qemu-devel@nongnu.org; Thu, 02 Apr 2026 17:57:25 -0400","from mail-ej1-x62b.google.com ([2a00:1450:4864:20::62b])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)\n (Exim 4.90_1) (envelope-from )\n id 1w8Q2T-0007CW-VD\n for qemu-devel@nongnu.org; Thu, 02 Apr 2026 17:57:23 -0400","by mail-ej1-x62b.google.com with SMTP id\n a640c23a62f3a-b7cf4a975d2so176158166b.2\n for ; Thu, 02 Apr 2026 14:57:21 -0700 (PDT)","from thinkpad-t470s.. (93-143-182-244.adsl.net.t-com.hr.\n [93.143.182.244]) by smtp.googlemail.com with ESMTPSA id\n a640c23a62f3a-b9c3cac0e1asm134009166b.27.2026.04.02.14.57.18\n (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n Thu, 02 Apr 2026 14:57:19 -0700 (PDT)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=gmail.com; s=20251104; t=1775167040; x=1775771840; darn=nongnu.org;\n h=content-transfer-encoding:mime-version:references:in-reply-to\n :message-id:date:subject:cc:to:from:from:to:cc:subject:date\n :message-id:reply-to;\n bh=Iq6P3SESs/IOCtPL61KoE1DsZM3683YfrNg3jTL5uxc=;\n b=N3lcUhX315uXxCps8mesZsW4BlznRcdmf1RaNaShhwHw4NcLcWnZyB8E1nmZTrVpZs\n 8mEzC3F9hlkz93b/FGEJF1eSOVK/P4AxJb1JPRIuWO6Ig4I2TF8rWpgAXnKSLNWeP2pA\n xpj2B5BYnBfRAt+8XZkwO9ODjcE6hRW4PnggimQYJmzUvaXHxkToreyQx9n2vBk8d10G\n CmlmNVFHFGTj0XlwBDE+Y/ZMU5vdxorUiLpvt/vH0UKQ3k6JcAgZt+PIwSpUwFEFkKcY\n 70i4Q3cGRoJzm5aKi2PryL9FC1+88Fr+PbiOsWRTXQasQdd/bYyIDoft4jWZ5L8KicpI\n dgbA==","X-Google-DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20251104; t=1775167040; x=1775771840;\n h=content-transfer-encoding:mime-version:references:in-reply-to\n :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from\n :to:cc:subject:date:message-id:reply-to;\n bh=Iq6P3SESs/IOCtPL61KoE1DsZM3683YfrNg3jTL5uxc=;\n b=SKfnODClgUPVUSa5KKXrGbiyI7bJAF32C5rQ3axVF6eZaS7nBQooKVPgAh2O5ZoKPr\n yJN/nBrfNgMgThy9RgWwCXNrG40HQK85yFep07PRY0IkgN6ySYso8+1M4l5l0FRl9mLv\n rbt9sK5Y9rrOQY4EhrvWi/WL48JE5/eeWoM7LPKOKT1r8bf1PBzjKdLbnZaIIFnzihul\n VaGmg4RzrllDgzUEcJUv6fVh5IS9PkCHz9SNGjUzPxr+gQSAesGFLQJtXmHzndvr6usN\n C4Jvchr2jjYBckLfQwHexauuUs989O4GJgZH/CpejKym8U5CKTMtCxd6E7zfcrETW0gq\n /9Mw==","X-Gm-Message-State":"AOJu0YxRFHau29qinc+zTjhs/ab8WcLxTVGt/T3tj5UaFe2Xnalq/AVb\n yQGwh+sXyzO+O6iiOOt5Ys1LXEXg4gguhY/iRd7dgRryR8Sf6jvCkxSBQzUkNEys","X-Gm-Gg":"AeBDieuBDnaFWNwJF/gCK9mecdQ6AN9PeTuNMMUrKqfCV1i7xfAHXTFXEJawegHLm4w\n mp0V1nI+ZXxmCIiAlLyHGtTM2eMijCj8+CG7dOPDuor6IGqtaKWMP1lRwe5bNgyDmoyt0EobE90\n /HZ9qs/dQLXPy7KrxPJN9aivHS/kQTiMlPPvisa/sOKx55RMDvBb4MyAYCubZPq9nl5IiTTqOLZ\n e3GMowFUR5++T5UJy0RWE+78ZW9By5HAZernqDPyvbswy8fmHSkvclwSE8QdNd7wcrFRmEfkAim\n mXBED2+W5/6ZQpCiyM7IqDnQoEm5lpzpbwrjJlILC3vv5wS/r9bmoeZ3Bn4pmP+AYtG3aeusPQM\n Se5XpN0fvkZ4eZpwSAa6PJ3qEbax4my+FiUbbf8K1q4YXH/TQYAkL0IQEiLXDXGYXqFrei9gD5H\n Ib64XakjuyLrFtvoVI2pwbX+evwOv2ZwzXgjYA2WJpzIE393uCrbReo444pBexCj/YioK1lkkDd\n xVYwPG7","X-Received":"by 2002:a17:907:a44:b0:b9b:207c:f7b7 with SMTP id\n a640c23a62f3a-b9c6768d2e2mr27200266b.3.1775167039942;\n Thu, 02 Apr 2026 14:57:19 -0700 (PDT)","From":"Ruslan Ruslichenko ","To":"qemu-devel@nongnu.org","Cc":"qemu-arm@nongnu.org, alex.bennee@linaro.org, peter.maydell@linaro.org,\n artem_mygaiev@epam.com, volodymyr_babchuk@epam.com,\n takahiro.nakata.wr@renesas.com,\n \"Edgar E . Iglesias\" ,\n Ruslan_Ruslichenko@epam.com, balaton@eik.bme.hu","Subject":"[PATCH v3 21/33] hw/arm/arm_generic_fdt: Add support for host-backed\n RAM regions","Date":"Thu, 2 Apr 2026 23:56:06 +0200","Message-ID":"<20260402215629.745866-22-ruslichenko.r@gmail.com>","X-Mailer":"git-send-email 2.43.0","In-Reply-To":"<20260402215629.745866-1-ruslichenko.r@gmail.com>","References":"<20260402215629.745866-1-ruslichenko.r@gmail.com>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Received-SPF":"pass client-ip=2a00:1450:4864:20::62b;\n envelope-from=ruslichenko.r@gmail.com; helo=mail-ej1-x62b.google.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,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=unavailable 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":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"From: Ruslan Ruslichenko \n\nAdd the ability to dynamically map QEMU host memory backends to\nguest memory using configuration from the Device Tree.\n\nTo map a host memory backend, memory region nodes with the\n'qemu-memory-region' compatible string and the 'qemu,ram' property\nmust specify a 'qemu,host-id' property containing the memdev name.\n\nThe corresponding memory backends can be specified via the command line:\n\n...\n-object memory-backend-file,id=mem0,mem-path=memory.img,size=256M\n...\n\nIf no host backend is found, the initialization will fall back to\nstandard anonymous memory mapping.\n\nSigned-off-by: Ruslan Ruslichenko \n---\n hw/arm/arm_generic_fdt.c | 96 +++++++++++++++++++++++++++++++++++++++-\n 1 file changed, 95 insertions(+), 1 deletion(-)","diff":"diff --git a/hw/arm/arm_generic_fdt.c b/hw/arm/arm_generic_fdt.c\nindex 7b50957a82..de121820e0 100644\n--- a/hw/arm/arm_generic_fdt.c\n+++ b/hw/arm/arm_generic_fdt.c\n@@ -43,6 +43,98 @@ struct ARMGenericFDTState {\n \n OBJECT_DECLARE_SIMPLE_TYPE(ARMGenericFDTState, ARM_GENERIC_FDT_MACHINE)\n \n+static void map_host_memdev_node(FDTMachineInfo *fdti, const char *node_path)\n+{\n+ int len;\n+ uint64_t mr_size, backed_size;\n+ Object *mem_obj;\n+ Object *backend_obj;\n+ MemoryRegion *mr;\n+ MemoryRegion *backend_mr;\n+ MemoryRegion *container;\n+ HostMemoryBackend *backend_mem;\n+\n+ const char *compat = qemu_fdt_getprop(fdti->fdt, node_path,\n+ \"compatible\", &len, NULL);\n+ const char *host_id = qemu_fdt_getprop(fdti->fdt, node_path, \"qemu,host-id\",\n+ &len, NULL);\n+ bool is_qemu_ram = (qemu_fdt_getprop(fdti->fdt, node_path, \"qemu,ram\",\n+ &len, NULL) != NULL);\n+\n+ if (!compat || strcmp(compat, \"qemu-memory-region\")) {\n+ return;\n+ }\n+\n+ if (!is_qemu_ram || !host_id) {\n+ return;\n+ }\n+\n+ mem_obj = fdt_init_get_opaque(fdti, node_path);\n+ if (!mem_obj) {\n+ return;\n+ }\n+\n+ backend_obj = object_resolve_path_type(host_id, TYPE_MEMORY_BACKEND,\n+ NULL);\n+ if (!backend_obj) {\n+ warn_report(\"No mem backend found for FDT requested host-id %s\",\n+ host_id);\n+ return;\n+ }\n+\n+ backend_mem = MEMORY_BACKEND(backend_obj);\n+ backend_mr = host_memory_backend_get_memory(backend_mem);\n+\n+ mr = MEMORY_REGION(mem_obj);\n+ container = mr->container;\n+ if (!container) {\n+ warn_report(\"No parent found for requested host-id %s\",\n+ host_id);\n+ return;\n+ }\n+\n+ mr_size = memory_region_size(mr);\n+ backed_size = memory_region_size(backend_mr);\n+\n+ if (backed_size != mr_size) {\n+ error_report(\"Unable to map host backed memory: %s, \"\n+ \"dts size: 0x%\" PRIx64 \", but memdev size: 0x%\" PRIx64,\n+ host_id, mr_size, backed_size);\n+ exit(1);\n+ }\n+\n+ hwaddr base_addr = mr->addr;\n+\n+ memory_region_del_subregion(container, mr);\n+ memory_region_add_subregion(container, base_addr, backend_mr);\n+\n+ fdt_init_set_opaque(fdti, node_path, OBJECT(backend_mr));\n+ object_unparent(mem_obj);\n+}\n+\n+/* Parse device-tree starting from 'node' and attach file-backed RAM's */\n+static void map_host_memdevs(FDTMachineInfo *fdti, const char *node_path)\n+{\n+ int i;\n+ char **children;\n+ int num_children = qemu_devtree_get_num_children(fdti->fdt, node_path);\n+\n+ if (num_children > 0) {\n+ children = g_malloc0(sizeof(*children) * num_children);\n+\n+ num_children = qemu_devtree_get_children(fdti->fdt, node_path,\n+ num_children, children);\n+ for (i = 0; i < num_children; ++i) {\n+ map_host_memdevs(fdti, children[i]);\n+ g_free(children[i]);\n+ }\n+\n+ g_free(children);\n+ }\n+\n+ map_host_memdev_node(fdti, node_path);\n+}\n+\n static void init_machine(void *fdt, ARMGenericFDTState *s)\n {\n FDTMachineInfo *fdti;\n@@ -63,7 +155,9 @@ static void init_machine(void *fdt, ARMGenericFDTState *s)\n /* Instantiate peripherals from the FDT. */\n fdti = fdt_generic_create_machine(fdt, NULL);\n \n- mem_area = MEMORY_REGION(object_resolve_path(node_path[0], NULL));\n+ map_host_memdevs(fdti, \"/\");\n+\n+ mem_area = MEMORY_REGION(fdt_init_get_opaque(fdti, node_path[0]));\n \n s->bootinfo.loader_start = object_property_get_int(OBJECT(mem_area),\n \"addr\", NULL);\n","prefixes":["v3","21/33"]}