From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40017) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZgJVV-00052Q-FC for qemu-devel@nongnu.org; Sun, 27 Sep 2015 17:29:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZgJVS-0005a8-95 for qemu-devel@nongnu.org; Sun, 27 Sep 2015 17:29:17 -0400 Received: from relay-06.andrew.cmu.edu ([128.2.157.21]:60901 helo=relay.andrew.cmu.edu) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZgJVS-0005Zj-1g for qemu-devel@nongnu.org; Sun, 27 Sep 2015 17:29:14 -0400 From: "Gabriel L. Somlo" Date: Sun, 27 Sep 2015 17:29:02 -0400 Message-Id: <1443389342-2186-6-git-send-email-somlo@cmu.edu> In-Reply-To: <1443389342-2186-1-git-send-email-somlo@cmu.edu> References: <1443389342-2186-1-git-send-email-somlo@cmu.edu> Subject: [Qemu-devel] [PATCH v4 5/5] fw_cfg: document ACPI device node information List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, drjones@redhat.com, matt.fleming@intel.com, ehabkost@redhat.com, mst@redhat.com, zhaoshenglong@huawei.com, leif.lindholm@linaro.org, ard.biesheuvel@linaro.org, kevin@koconnor.net, kraxel@redhat.com, pbonzini@redhat.com, imammedo@redhat.com, markmb@redhat.com, lersek@redhat.com, rth@twiddle.net Signed-off-by: Gabriel Somlo --- docs/specs/fw_cfg.txt | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt index bc95404..4d85701 100644 --- a/docs/specs/fw_cfg.txt +++ b/docs/specs/fw_cfg.txt @@ -77,6 +77,15 @@ increasing address order, similar to memcpy(). Selector Register IOport: 0x510 Data Register IOport: 0x511 +== ACPI Interface == + +The fw_cfg device is defined with ACPI ID "QEMU0002". Since we expect +ACPI tables to be passed into the guest through the fw_cfg device itself, +the guest-side BIOS can not use ACPI to find fw_cfg. However, once the +bios is finished setting up ACPI tables and hands control over to the +guest kernel, the latter can use the fw_cfg ACPI node for a more accurate +inventory of in-use IOport or MMIO regions. + == Firmware Configuration Items == === Signature (Key 0x0000, FW_CFG_SIGNATURE) === -- 2.4.3