Linux PCI Express Hotplug Questions.

Linux PCI Express Hotplug Questions.

[chi]

Hi all,

I'm trying to understand a few things about the hot plug support
in the recent versions of Linux. I'm particularly interested in
how PCIe devices are handled. 

From reading various documentation on the Internet, I have so far
gathered: 

1. PCIe hotswap/hotplug is supported as of 2.6.19 (but I am not
   100% sure if I am correct).

2. To support native hotswap in the O.S, the firmware in the BIOS
   must provide the OSHP/_OSC method. 

3. Depending on the state of the BIOS's firmware, one of the
   following drivers should be used: 

   pciehp
   shpchp
   acpihp

And now, my questions:

1. When I insert a PCIe device into a live system, which part(s) 
   of Linux detects the presence of the new device? I have a brief
   understanding about the interactions between kobjects, sysfs,
   /sbin/hotplug, modutils, and udev. I just can't seem to pin 
   point the code which detects the new device that causes the 
   hot plug events to be generated. Similarly, which code detects
   the absence of a device, if the device is surprise hot swapped.

2. What does it really mean when I see the message "OS has native 
   control"? If the OS does not get native control, for whatever
   reason, does that mean I can't do hot plug with my device?

3. Which kernel driver should I be using between pciehp, shpchp, and 
   acpihp? 

Many thanks,
Chi


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Re: Linux PCI Express Hotplug Questions.

[Greg KH]

On Tue, Apr 10, 2007 at 05:21:57AM -0500, chi@artesyncp.com wrote:
> Hi all,
> 
> I'm trying to understand a few things about the hot plug support
> in the recent versions of Linux. I'm particularly interested in
> how PCIe devices are handled. 

Try asking on the linux PCI hotplug mailing list.  It's availble at:
	pcihpd-discuss@lists.sourceforge.net

good luck,

greg k-h

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