Date: Tue, 24 Aug 2010 10:05:20 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: jhb@FreeBSD.org Cc: yanegomi@gmail.com, freebsd-hackers@FreeBSD.org Subject: Re: Why doesn't ppc(4) check non-ENXIO failures during probe? Message-ID: <20100824.100520.826498698880464924.imp@bsdimp.com> In-Reply-To: <201008241009.46624.jhb@freebsd.org> References: <201008171615.21103.jhb@freebsd.org> <20100823.220945.232861953240012158.imp@bsdimp.com> <201008241009.46624.jhb@freebsd.org>
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In message: <201008241009.46624.jhb@freebsd.org>
John Baldwin <jhb@FreeBSD.org> writes:
: On Tuesday, August 24, 2010 12:09:45 am M. Warner Losh wrote:
: > In message: <201008171615.21103.jhb@freebsd.org>
: > John Baldwin <jhb@FreeBSD.org> writes:
: > : > So more or less it's for BIOSes with ISA that doesn't feature plug
: > : > and play (286s, 386s, some 486s?)? Just trying to fill in the gap :).
: > :
: > : Yes, it may perhaps still be useful for some x86 embedded systems, though
: > : it is doubtful that those would use a ppc(4) device perhaps.
: >
: > Many embedded x86 systems use ppc(4) as a DIO port. ppi attaches to
: > it and can be used to frob bits.
: >
: > These days, of course, almost all boards have ACPI, so that means they
: > get enumerated that way. Only boards that don't run windows might not
: > have ACPI, in which case the devices are usually enumerated via
: > PNPBIOS. But not always, since those boards tend to have the buggiest
: > BIOSes on the planet in this area. Hints are needed on a few of these
: > boards since nothing else will work. And they have Atom processors on
: > them...
:
: The specific code I am referring to is the code in ppc_isa_probe() that tries
: to auto-identify a ppc port by poking at various I/O ports directly. It is
: not enabled by default. You'd have to have a ppc hint that did not include an
: I/O port for this code to be triggered I think as it only gets executed if a
: ppc(4) device does not have an I/O port resource from ACPI/PnPBIOS/hints.
Ah, that code... Yes, you're right...
: I was mostly thinking of this in terms of ISA cards, and I doubt that even
: modern embedded systems have ISA slots. :)
There are still a few PC-104 boards knocking around (which is ISA in a
different form-factor), but mostly people have moved PC-104+ which is
really PCI or other things...
Warner
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