rt_request_global_irq vs rt_request_linux_irq

[Nikita V. Youshchenko]

> 
> Hi,
> 
>   I would like to do some time stamping on my network
> card's interrupt requests.  with rt_request_linux_irq,
> it works great but I am afraid the values return are
> not really real time since it is treated by the linux
> irq system.  When I try to use the
> rt_request_global_irq on my nic's irq it freezes up
> the whole system.  I do the request, the startup_irq
> and also the pend_linux...  I wonder what I am doing
> wrong which makes the system crash.  I am using the
> module 8139too.o for the Realtek 8139c nic.  My isr is
> running as a kernel module.  Well any hint would be
> appreciate if someone will.

Possibvle reasons:
- your ISR returns with Linux interrupts disabled;
- your ISR (or something called from it) uses a spinlock then something in 
Linux also uses, and at some moment Linux is interrupted with that spinlock 
is locked. In general, it is not safe to use Linux drivers in hard rt mode.