From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Date: Mon, 01 Nov 2004 18:56:10 +0000 Subject: Re: PCI hotplug Message-Id: <20041101185610.GA14808@kroah.com> List-Id: References: <1098903129.17422.2.camel@duffman> In-Reply-To: <1098903129.17422.2.camel@duffman> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org 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 ------------------------------------------------------- This SF.Net email is sponsored by: Sybase ASE Linux Express Edition - download now for FREE LinuxWorld Reader's Choice Award Winner for best database on Linux. http://ads.osdn.com/?ad_idU88&alloc_id065&op=click _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel