From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gabriel L. Somlo" Subject: [PATCH v6 5/5] fw_cfg: document ACPI device node information Date: Wed, 27 Jan 2016 22:02:41 -0500 Message-ID: <1453950161-13252-6-git-send-email-somlo@cmu.edu> References: <1453950161-13252-1-git-send-email-somlo@cmu.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <1453950161-13252-1-git-send-email-somlo@cmu.edu> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org To: gregkh@linuxfoundation.org, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, arnd@arndb.de, lersek@redhat.com, ralf@linux-mips.org, rmk+kernel@arm.linux.org.uk, eric@anholt.net, hanjun.guo@linaro.org, zajec5@gmail.com, sudeep.holla@arm.com, agross@codeaurora.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Cc: peter.maydell@linaro.org, ehabkost@redhat.com, ard.biesheuvel@linaro.org, matt@codeblueprint.co.uk, stefanha@gmail.com, mst@redhat.com, qemu-devel@nongnu.org, leif.lindholm@linaro.org, luto@amacapital.net, kraxel@redhat.com, pbonzini@redhat.com, imammedo@redhat.com, revol@free.fr, rth@twiddle.net List-Id: devicetree@vger.kernel.org Signed-off-by: Gabriel Somlo Reviewed-by: Laszlo Ersek Reviewed-by: Marc Mar=C3=AD --- 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) =20 +=3D=3D ACPI Interface =3D=3D + +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 t= he +firmware is finished setting up ACPI tables and hands control over to th= e +guest kernel, the latter can use the fw_cfg ACPI node for a more accurat= e +inventory of in-use IOport or MMIO regions. + =3D=3D Firmware Configuration Items =3D=3D =20 =3D=3D=3D Signature (Key 0x0000, FW_CFG_SIGNATURE) =3D=3D=3D --=20 2.4.3