PERFORCE change 52156 for review

[Nate Lawson]

On Thu, 13 May 2004, Takanori Watanabe wrote:
> In message <20040512174010.L85042 at root.org>, Nate Lawson wrote:
> >You bring up a problem that I've been having also.  When I commit the ACPI
> >performance states driver, it needs to be able to get an ACPI handle.  My
> >solution to this is to have multiple drivers with the same name.  Only the
> >acpi one will supply a handle to the processor object.
> >legacy mode:
> >legacy0
> >        cpu0 (implemented in legacy.c)
> >             speedstep0
> >
> >acpi mode:
> >acpi0
> >        cpu0 (implemented in acpi_cpu.c)
> >             acpi_perf0
> >             speedstep0
> >
> >In the legacy case, acpi_perf's probe method will be called but it will
> >return ENXIO because the non-acpi cpu0 will always return NULL for the
> >ACPI_HANDLE ivar.  It's kind of lame because it requires two different
> >drivers to implement the same ivars but it's the only way I could figure
> >out to allow both non-acpi and acpi-based cpufreq drivers attach.
>
> In this case, pci1 and its children know ACPI handle, if
> ACPI vga extension is appeard in the name space tree.
> You will see this by devinfo(8) with -v option. So the
> role of video0 driver is manage child drivers.
> All request may forwarded to the grand parent.

I guess I haven't looked closely enough at acpi_pci.c.  So it calls child
probe based on _ADR data in child ACPI objects via WalkNamespace?  Does it
then call normal pci config register probe for devices that don't appear
in the acpi namespace?

> >> >There is DPMS on Sparc, for example, although I don't know how it is
> >> >implemented.
> >>
> >> Should we have to imprement machine independent in-kernel VM86
> >> by emulating real mode x86? This will be needed for especially
> >> amd64/ia32e, which inherits many assets from ia32.
> >
> >I thought DPMS on sparc was through openfirmware or some other non-x86
> >device.
>
> XFree86 has x86 emulator to use vga bios for initializing in other
> archtecture.

Ah, interesting.  I hope we don't have to go this far in FreeBSD.  It
would be important to talk to Nicholas Souchu.
http://people.freebsd.org/~nsouch/kgi4BSD/content-home.html

-Nate