From: Greg KH <greg@kroah.com>
To: linux-hotplug@vger.kernel.org
Subject: Re: PCI hotplug
Date: Mon, 01 Nov 2004 18:56:10 +0000 [thread overview]
Message-ID: <20041101185610.GA14808@kroah.com> (raw)
In-Reply-To: <1098903129.17422.2.camel@duffman>
On Mon, Nov 01, 2004 at 09:19:31AM -0800, Tom Duffy wrote:
> On Fri, 2004-10-29 at 21:03 -0700, Greg KH wrote:
> > On Wed, Oct 27, 2004 at 11:52:09AM -0700, Tom Duffy wrote:
> > > Greg, et. al,
> > >
> > > Is there a document out there describing in detail how PCI hotplug works
> > > under Linux?
> >
> > From a kernel viewpoint, or from a userspace viewpoint? For 2.4 or
> > 2.6?
>
> kernel, 2.6
>
> > Did you take a look at the acpi pci hotplug driver in the kernel?
> > Source is always your best documentation :)
>
> Yes, I started to go through it. And I was afraid you were going to say
> that :-)
Heh.
> > Anything specific you are wondering about?
>
> Well, we are building a system that will have PCI-E hotplug and I need
> to make sure that Linux will support it.
>
> I am under the impression that Windows uses ACPI to tell the BIOS to
> stimulate the hotplug controller registers. In general, Linux has
> relied less on the BIOS to handle system management, instead
> implementing all the bits in the OS.
For some controllers, yes, Linux implements all the bits. For some, it
has to use ACPI, no other way to do it. Linux supports both, depending
on the hardware you have.
There's a driver in the kernel that should work for any hotplug
controller that matches the SHPC spec. Examples of this include both
AMD's hardware, and Intel's hardware, so I feel good about this driver
matching the published spec.
For PCI-E, we also have a driver that doesn't rely on ACPI. However it
may be pretty much tied to a specific PCI-E implementation from Intel,
as I don't know of any other chipsets that support PCI-E and hotplug
today.
> With proper support from the OS, the driver itself could use interrupts
> from the standard hotplug controller in the host's root PCI bridge to
> handle hotplug events.
>
> So, what does Linux do?
As described above, both, depending on your hardware. Probably not what
you wanted to hear :)
thanks,
greg k-h
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next prev parent reply other threads:[~2004-11-01 18:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-27 18:52 PCI hotplug Tom Duffy
2004-10-30 4:03 ` Greg KH
2004-11-01 17:19 ` Tom Duffy
2004-11-01 18:56 ` Greg KH [this message]
2004-12-09 15:24 ` PCI HotPlug Tejas Sumant
2004-12-09 23:40 ` Greg KH
2004-12-10 0:16 ` Linas Vepstas
2004-12-10 0:22 ` Greg KH
2004-12-10 0:39 ` Linas Vepstas
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