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| author | Gabriel L. Somlo <somlo@cmu.edu> | 2016-02-19 13:20:29 -0500 |
|---|---|---|
| committer | Gerd Hoffmann <kraxel@redhat.com> | 2016-03-08 12:15:22 +0100 |
| commit | 36a43ea83b4426344592523fd560e5f76c4867c4 (patch) | |
| tree | 05b23523e7284bff890a44adab8cd9502f9278b9 /docs | |
| parent | 70bee80d6b6cfa3ad888ee20332ddfb826a80249 (diff) | |
| download | qemu-36a43ea83b4426344592523fd560e5f76c4867c4.tar.gz | |
fw_cfg: document ACPI device node information
Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Marc Marí <markmb@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 1455906029-25565-6-git-send-email-somlo@cmu.edu
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/specs/fw_cfg.txt | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt index 2099ad9a4d..5414140f33 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) === |