From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56939) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZxR1p-0002s7-8d for qemu-devel@nongnu.org; Fri, 13 Nov 2015 21:57:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZxR1m-0000n3-14 for qemu-devel@nongnu.org; Fri, 13 Nov 2015 21:57:25 -0500 Received: from relay-04.andrew.cmu.edu ([128.2.105.169]:45332 helo=relay.andrew.cmu.edu) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZxR1l-0000mk-TH for qemu-devel@nongnu.org; Fri, 13 Nov 2015 21:57:21 -0500 From: "Gabriel L. Somlo" Date: Fri, 13 Nov 2015 21:57:18 -0500 Message-Id: <1447469838-13533-6-git-send-email-somlo@cmu.edu> In-Reply-To: <1447469838-13533-1-git-send-email-somlo@cmu.edu> References: <1447469838-13533-1-git-send-email-somlo@cmu.edu> Subject: [Qemu-devel] [PATCH v5 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, matt.fleming@intel.com, ehabkost@redhat.com, mst@redhat.com, ard.biesheuvel@linaro.org, leif.lindholm@linaro.org, kraxel@redhat.com, pbonzini@redhat.com, imammedo@redhat.com, markmb@redhat.com, lersek@redhat.com, rth@twiddle.net Signed-off-by: Gabriel Somlo Reviewed-by: Laszlo Ersek --- 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 2099ad9..5414140 100644 --- a/docs/specs/fw_cfg.txt +++ b/docs/specs/fw_cfg.txt @@ -84,6 +84,15 @@ Selector Register address: Base + 8 (2 bytes) Data Register address: Base + 0 (8 bytes) DMA Address address: Base + 16 (8 bytes) +== 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 firmware can not use ACPI to find fw_cfg. However, once the +firmware 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