gmane.linux.kernel

how to link to hrtimers in the kernel

Hi all,

I have modified drivers/usb/core/devio.c to use hrtimer_nanosleep(), and 
have included linux/hrtimer.h with it.

But now I am having trouble linking, I get:
ERROR: "hrtimer_nanosleep" [drivers/usb/core/usbcore.ko] undefined!

How do I properly link to the hrtimer library?

Thanks!
George

headers

Randy.Dunlap | 6 Oct 18:33

[patch] Re: how to link to hrtimers in the kernel

On Mon, 6 Oct 2008, George Nychis wrote:

> Hi all,
> 
> I have modified drivers/usb/core/devio.c to use hrtimer_nanosleep(), and have
> included linux/hrtimer.h with it.
> 
> But now I am having trouble linking, I get:
> ERROR: "hrtimer_nanosleep" [drivers/usb/core/usbcore.ko] undefined!
> 
> How do I properly link to the hrtimer library?

Hi,
That function needs to be exported in its source file.
Patch below should fix it for you.

From: Randy Dunlap <randy.dunlap <at> oracle.com>

Export hrtimer_nanosleep() for module use.

Signed-off-by: Randy Dunlap <randy.dunlap <at> oracle.com>
---
 kernel/hrtimer.c |    1 +
 1 file changed, 1 insertion(+)

--- linux-2.6.27-rc8-git5.orig/kernel/hrtimer.c
+++ linux-2.6.27-rc8-git5/kernel/hrtimer.c
@@ -1559,6 +1559,7 @@ out:
 	destroy_hrtimer_on_stack(&t.timer);
 	return ret;

(Continue reading)

headers

Thomas Gleixner | 6 Oct 18:51

Re: [patch] Re: how to link to hrtimers in the kernel

On Mon, 6 Oct 2008, Randy.Dunlap wrote:
> On Mon, 6 Oct 2008, George Nychis wrote:
> 
> > Hi all,
> > 
> > I have modified drivers/usb/core/devio.c to use hrtimer_nanosleep(), and have
> > included linux/hrtimer.h with it.

Please do not use hrtimer_nanosleep() in drivers. That's
wrong.

What do you want to achieve ?

> Export hrtimer_nanosleep() for module use.

NAK, hrtimer_nanosleep is part of the user space interfaces.

> Signed-off-by: Randy Dunlap <randy.dunlap <at> oracle.com>
> ---
>  kernel/hrtimer.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> --- linux-2.6.27-rc8-git5.orig/kernel/hrtimer.c
> +++ linux-2.6.27-rc8-git5/kernel/hrtimer.c
> @@ -1559,6 +1559,7 @@ out:
>  	destroy_hrtimer_on_stack(&t.timer);
>  	return ret;
>  }
> +EXPORT_SYMBOL_GPL(hrtimer_nanosleep);
>

(Continue reading)

headers

George Nychis | 6 Oct 19:16

Re: [patch] Re: how to link to hrtimers in the kernel

Thomas Gleixner wrote:
> On Mon, 6 Oct 2008, Randy.Dunlap wrote:
>> On Mon, 6 Oct 2008, George Nychis wrote:
>>
>>> Hi all,
>>>
>>> I have modified drivers/usb/core/devio.c to use hrtimer_nanosleep(), and have
>>> included linux/hrtimer.h with it.
> 
> Please do not use hrtimer_nanosleep() in drivers. That's
> wrong.
> 
> What do you want to achieve ?
>  

I am trying to sleep at the microsecond level, which ssleep and msleep 
cannot provide.  I couldn't find any other nanosleep method in the kernel.

I found information by searching the net on using jiffies to accomplish 
sleep periods, but that is not high enough in resolution.

I'd greatly appreciate any feedback.

Thanks!
George

headers

Brian Pomerantz | 7 Oct 16:55

Re: [patch] Re: how to link to hrtimers in the kernel

On Mon, Oct 06, 2008 at 01:16:15PM -0400, George Nychis wrote:
> 
> I am trying to sleep at the microsecond level, which ssleep and msleep 
> cannot provide.  I couldn't find any other nanosleep method in the kernel.
> 
> I found information by searching the net on using jiffies to accomplish 
> sleep periods, but that is not high enough in resolution.
> 
> I'd greatly appreciate any feedback.
> 

Is there any reason you can't use udelay()/ndelay()?

BAPper