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Date: Sat, 21 Apr 2001 13:41:00 +0200 (CEST)
From: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
cc: Dennis <dennis@etinc.com>, Matti Aarnio <matti.aarnio@zmailer.org>,
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Subject: Re: SMP in 2.4
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On Sat, 21 Apr 2001, Alan Cox wrote:

> > > especially if you want to do it right on the BX. But you can do this and rtlinux
> > > does
> > 
> > There is already desc->handler->ack(irq) in do_IRQ which does that. Is any
> > more special handling needed? 
> 
> You need to keep the IRQ line masked not just ack it.

desc->handler->ack could be mask_and_ack_8259A, ack_edge_ioapic_irq,
mask_and_ack_level_ioapic_irq or ack_lapic_irq - it does exactly that -
masking and acking an interrupt. 

> The code for handling all
> the BX and other cases is there but its a bit more than 3 clock cycles long

What magic does it have to do? Where is it in kernel?

Mikulas

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