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-   -   Bug#616720: linux-image-2.6-xen-amd64: Feature request -- Serial driver serial8250 as module (http://www.linux-archive.org/debian-kernel/498003-bug-616720-linux-image-2-6-xen-amd64-feature-request-serial-driver-serial8250-module.html)

David Ruetti 03-06-2011 08:35 PM

Bug#616720: linux-image-2.6-xen-amd64: Feature request -- Serial driver serial8250 as module
 
Package: linux-image-2.6-xen-amd64
Version: 2.6.32+29
Severity: wishlist
Tags: upstream


Please compile serial driver serial8250 as module instead into the kernel.


-- System Information:
Debian Release: 6.0
APT prefers stable
APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.32-5-xen-amd64 (SMP w/2 CPU cores)



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David Rütti 03-07-2011 11:14 AM

Bug#616720: linux-image-2.6-xen-amd64: Feature request -- Serial driver serial8250 as module
 
Hello Ben

*

Thank you for your quick reply!

*


> > Please compile serial driver serial8250 as module instead into the kernel.
>
> Serial console support requires the serial driver to be built-in.


OK. Has this been changed in Xen 4.0 and kernel 2.6.32? Before squeeze was released, I have been using c't server with*xen 3*and kernel 2.6.18 and the driver serial8250 was compiled as module.

*

I would like to provide a DomU serial port access according to the xen-wiki http://wiki.xensource.com/xenwiki/InstallationNotes. Before it worked stable. Do you have an idea what I could try? As far as I am informed, pvusb is currently not working in squeeze.

*

David

*

Bastian Blank 03-07-2011 05:50 PM

Bug#616720: linux-image-2.6-xen-amd64: Feature request -- Serial driver serial8250 as module
 
tags 616720 + moreinfo - upstream
thanks

On Sun, Mar 06, 2011 at 10:35:42PM +0100, David Ruetti wrote:
> Please compile serial driver serial8250 as module instead into the kernel.

Please explain why.

Bastian

--
The heart is not a logical organ.
-- Dr. Janet Wallace, "The Deadly Years", stardate 3479.4



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David Rütti 03-08-2011 11:23 AM

Bug#616720: linux-image-2.6-xen-amd64: Feature request -- Serial driver serial8250 as module
 
*Hello Bastian

*

> > Please compile serial driver serial8250 as module instead into the kernel.
>
> Please explain why.


I*would like to provide a DomU serial port access according to the xen-wiki.

*

To have access to the serial port in DomU, we need to prevent Dom0 from taken hold of this piece of hardware
add to /etc/hotplug/blacklist the following modules to exclude from being loaded
8250
8250_pnp
serial_core
*
domU config:
irq*=*[*4*]
ioports*=*[*"3f8-3ff"*]
to load the modules in domU.

*

I tried without unload the 8250 driver and starting the domU resuted in an IRQ 4*error.

*

Kind regards

*

David

Ian Campbell 03-08-2011 01:26 PM

Bug#616720: linux-image-2.6-xen-amd64: Feature request -- Serial driver serial8250 as module
 
On Tue, 2011-03-08 at 13:23 +0100, David Rütti wrote:
>
> Hello Bastian
>
> > > Please compile serial driver serial8250 as module instead into the
> kernel.
> >
> > Please explain why.
>
> I would like to provide a DomU serial port access according to the
> xen-wiki.
>
>
>
> To have access to the serial port in DomU, we need to prevent Dom0
> from taken hold of this piece of hardware
>
> add to /etc/hotplug/blacklist the following modules to exclude from
> being loaded
>
> 8250
>
> 8250_pnp
>
> serial_core
>
>
>
> domU config:
>
> irq = [ 4 ]
>
> ioports = [ "3f8-3ff" ]
>
> to load the modules in domU.
>
>
>
> I tried without unload the 8250 driver and starting the domU resuted
> in an IRQ 4 error.

So what you really need is to inhibit the 8250 driver from claiming the
ports/irqs associated with the serial points. I don't think you need to
inhibit the driver loading to do this.

I think this can be done with "8250.nr_uarts=0" on your domain 0 kernel
command line. (I've only ever used =1 myself but I'd expect =0 to work
by extension).

I see /sys/bus/platform/drivers/serial8250/{un,}bind on my systems, so
it's perhaps possible that you can also control this stuff even more
dynamically on a per-port basis too.

Ian.


>
>
>
> Kind regards
>
>
>
> David
>

--
Ian Campbell
Current Noise: Anathema - Thin Air

Government lies, and newspapers lie, but in a democracy they are different lies.




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David Rütti 03-09-2011 09:37 PM

Bug#616720: linux-image-2.6-xen-amd64: Feature request -- Serial driver serial8250 as module
 
Hello Ian

> > I tried without unload the 8250 driver and starting the domU resuted
> > in an IRQ 4 error.
>
> So what you really need is to inhibit the 8250 driver from claiming the
> ports/irqs associated with the serial points. I don't think you need to
> inhibit the driver loading to do this.
>
> I see /sys/bus/platform/drivers/serial8250/{un,}bind on my systems, so
> it's perhaps possible that you can also control this stuff even more
> dynamically on a per-port basis too.

Thanks a lot-lot for the hint!

I was indeed able to unbind the driver from the port with the following command:

echo -n "serial8250" > /sys/bus/platform/drivers/serial8250/unbind

And domU could be started with serial access!

The subject can also be closed.

Cheers

David

>
> Ian.


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