Re: [Openipmi-developer] IPMI device discovery [was Re: [PATCH ] IPMI: Locate the IPMI system interface in ACPI namespace]

Bjorn Helgaas
2009-11-18T21:19:22Z

On Wednesday 18 November 2009 01:40:57 pm Rocky Craig wrote:
> Bjorn Helgaas emitted:
>
> > Anything described by the SPMI should also be described in the namespace.
>
> I believe that distinction/request/requirement was lost "back in the day".

I disagree that this requirement was lost. The ACPI spec is regrettably
vague, but I think it still contains the very general requirement that
the ACPI namespace should describe everything that cannot be found by a
standard hardware enumeration mechanism.

That requirement allows the OS to use a single coherent device
discovery, driver binding, and resource management scheme to cover
all these devices. If we had to deal with all these devices piece-
meal, with an SPMI table here, an SPCR table there, we'd go more
mad than we already are.

There may be firmware that has an SPMI but neglects to put the device
in the namespace. In my opinion, that's clearly a defect. I think
it's unlikely since Windows relies on the namespace, but it's certainly
a risk.

Bjorn