Re: [rtl] help for a newbie

[David Olofson <david.olofson@reologica.se>]

On Wednesday 05 September 2001 15:39, Loren Frank wrote:
> Hi all. I am new to rtlinux and I have a problem I need help with.
>
> Briefly, I need to take the bttv driver for a framegrabber card and
> modify it so that, every time an interrupt is generated, the interrupt
> service routine is serviced by the real time kernel and a timestamp is
> read from another card. I have the real time driver for the other card
> working, but when I tried to convert the interrupt service routine from
> the bttv-driver.c source,  I just ended up hanging the machine. I had
> hoped that a simple modification where I changed the request_irq to a
> rtl_request_irq and changed the interrupt service routine would do
> it....
>
> Can anyone point me toward a solution?

You can't safely run ISR code written for Linux under RTL.

Write a *new* ISR for RTL, do what you need in it, and then have it 
invoke the old bttv ISR using a soft interrupt, so that the latter can 
run in Linux context as usual.


//David Olofson --- Programmer, Reologica Instruments AB

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