On 08/13/2012 01:25 AM, Gleb Natapov wrote:
On Sun, Aug 12, 2012 at 08:22:12PM -0500, Corey Minyard wrote:
Patch 2 is complex and I don't fully understand what it is doing. A
quick scan leads me to believe it is constructing a dynamic SSDT -
though it's not clear why a dynamic SSDT is needed and why the
existing mechanism (see build_ssdt()) for generating dynamic SSDTs is
not used.
It is constructing an addition to the DSDT table that is tacked on
to the end of that table if IPMI is present. It is complex, but
building ACPI namespace data is complex, and the data is not fixed
length.
You do not need to construct IPMI device dynamically in DSDT. Write it
in AML and have _STA method that tells OSPM if device is present or not.
There are lots of different options for IPMI devices. There are three
different interface types, with two string lengths. They can all appear
at arbitrary places in I/O or memory space. They can have an interrupt
or not. I would like to be able to represent all off the possibilities
so users can simulate any arbitrary machine they want.
I considered writing it in AML 8 times and figuring the offsets to set
the various values, but that seems rather messy to me.
If the real desire is to have a single IPMI device type at a single
address with a single interrupt always on, we could do that. The BIOS
would still need a way to know that the device was present or not, so
something will have to be passed. I'm not sure that reading from the
standard address to detect the device is reliable enough, but that could
be done, too.
-corey
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