PCI hotplug

PCI hotplug

[Tom Duffy]

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Greg, et. al,

Is there a document out there describing in detail how PCI hotplug works
under Linux?  I have found stuff on how to implement a driver so it
works with PCI hotplug, but haven't found one on how PCI hotplug was
implemented in Linux.  I am specifically interested in how Linux
interacts with the BIOS and what protocols it uses, like ACPI.

Thanks,

-tduffy

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Re: PCI hotplug

[Greg KH]

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?

> I have found stuff on how to implement a driver so it
> works with PCI hotplug, but haven't found one on how PCI hotplug was
> implemented in Linux.  I am specifically interested in how Linux
> interacts with the BIOS and what protocols it uses, like ACPI.

Did you take a look at the acpi pci hotplug driver in the kernel?
Source is always your best documentation :)

Anything specific you are wondering about?

thanks,

greg k-h


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Re: PCI hotplug

[Tom Duffy]

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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 :-)

> 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.

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?

-tduffy

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Re: PCI hotplug

[Greg KH]

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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PCI HotPlug

[Tejas Sumant]

Hi All,

I have recently subcribed the list.
I dont know much about PCI hotplugging, but have knowledge about linux
kernel programming and device drivers.

Can anybody tell me what all things should I to enable
hotplugging of PCI device on linux?

Thanks in advance.

Tejas




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Re: PCI HotPlug

[Greg KH]

On Thu, Dec 09, 2004 at 08:42:26PM +0530, Tejas Sumant wrote:
> Hi All,
> 
> I have recently subcribed the list.
> I dont know much about PCI hotplugging, but have knowledge about linux
> kernel programming and device drivers.

There is a pci hotplug for linux specific mailing list.  Perhaps this
would be better there?

> Can anybody tell me what all things should I to enable
> hotplugging of PCI device on linux?

You need a motherboard that supports this functionality.  Do you have
this kind of hardware?  If so, just enable the configuration option in
your kernel, load up the proper pci hotplug controller driver, and then
have fun adding and removing your pci devices.

Simple really :)

thanks,

greg k-h


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Re: PCI HotPlug

[Linas Vepstas]

On Thu, Dec 09, 2004 at 03:40:47PM -0800, Greg KH was heard to remark:
> 
> There is a pci hotplug for linux specific mailing list.  Perhaps this
> would be better there?

Really?  Google can't find it.  I'm subscribed to this list because
I know of no other list that discusses linux hotplug issues.

--linas



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Re: PCI HotPlug

[Greg KH]

On Thu, Dec 09, 2004 at 06:16:36PM -0600, Linas Vepstas wrote:
> On Thu, Dec 09, 2004 at 03:40:47PM -0800, Greg KH was heard to remark:
> > 
> > There is a pci hotplug for linux specific mailing list.  Perhaps this
> > would be better there?
> 
> Really?  Google can't find it.  I'm subscribed to this list because
> I know of no other list that discusses linux hotplug issues.

So if Google doesn't find something it doesn't exist?  :)

https://lists.sourceforge.net/lists/listinfo/pcihpd-discuss is what you
want.

thanks,

greg k-h


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Re: PCI HotPlug

[Linas Vepstas]

On Thu, Dec 09, 2004 at 04:22:23PM -0800, Greg KH was heard to remark:
> On Thu, Dec 09, 2004 at 06:16:36PM -0600, Linas Vepstas wrote:
> > On Thu, Dec 09, 2004 at 03:40:47PM -0800, Greg KH was heard to remark:
> > > 
> > > There is a pci hotplug for linux specific mailing list.  Perhaps this
> > > would be better there?
> > 
> > Really?  Google can't find it.  I'm subscribed to this list because
> > I know of no other list that discusses linux hotplug issues.
> 
> So if Google doesn't find something it doesn't exist?  :)
> 
> https://lists.sourceforge.net/lists/listinfo/pcihpd-discuss is what you
> want.

Hmm. Appearently, I've even posted to it. How embarrassing :-/
Its a low traffic list.

--linas


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