[Qemu-devel] Re: [SeaBIOS] seabios: acpi: add _RMV control method for PCI devices

[Avi Kivity <avi@redhat.com>]

On 12/13/2010 11:03 AM, Gleb Natapov wrote:
> >  We could also deprecate the old port and use fwcfg for everything
> >  (try fwcfg, fall back to ae00).
> >
> fwcfg designed to be simple for easy use by firmware. It has two port
> one for index another for value, so its use is racy in multi-threaded SMP
> environment. DSDT code is executed in such environment. There is lock
> facility in AML, but why complicate things.

I prefer to remove complexity from interfaces and have it in the 
implementation instead.

> >  >>   We could do this in two ways: by adding a fwcfg client to the DSDT,
> >  >>   or by copying the information to system memory, and referencing
> >  >>   system memory from the DSDT.
> >  >>
> >  >This is even worse. It requires some fixed address to be shared between
> >  >DSDT and Seabios (or alternatively Seabios will have to generate this
> >  >part of DSDT dynamically).
> >  >
> >
> >  Could easily be something in the F segment.
> >
> Yes, but then we will have two magic values (fwcfg index + address
> in F segment) instead of one (address of pci hot-plug controller).

The F segment address is internal to SeaBIOS; it isn't an external 
interface.

-- 
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