2008-10-06 15:41:44

by George Nychis

Subject: 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

2008-10-06 16:33:29

by Randy Dunlap

Subject: [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 <[email protected]>

Export hrtimer_nanosleep() for module use.

Signed-off-by: Randy Dunlap <[email protected]>
---
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);

asmlinkage long
sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp)

2008-10-06 16:52:14

by Thomas Gleixner

Subject: 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 <[email protected]>
> ---
> 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);
>
> asmlinkage long
> sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp)
>

2008-10-06 17:16:35

by George Nychis

Subject: 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

2008-10-07 15:04:20

by Brian Pomerantz

Subject: 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