On Fri, Feb 19, 2016 at 01:20:29PM -0500, Gabriel L. Somlo wrote: > Signed-off-by: Gabriel Somlo <so...@cmu.edu> > Reviewed-by: Laszlo Ersek <ler...@redhat.com> > Reviewed-by: Marc Marí <mar...@redhat.com>
Reviewed-by: Michael S. Tsirkin <m...@redhat.com> > --- > 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
