thanks for the input Rajat. I have another follow up question how does one decide which interrupt number to use let for a pci device. can the number u chose be dynamic so that one doesn't run into any irq conflicts. thanks kbisla ---------------------------------------- > Date: Sat, 5 May 2007 08:21:53 +0530 > From: rajat.noida.india@xxxxxxxxx > To: 2500.pradeep@xxxxxxxxx > Subject: Re: Shared Interrupt handling. > CC: k_bisla@xxxxxxxxxxx; vapier.adi@xxxxxxxxx; kernelnewbies@xxxxxxxxxxxx > > On 5/4/07, pradeep singh wrote: > > On 5/4/07, Rajat Jain wrote: > > > Hi, > > > > > > > > The interrupts are disabled at the interrupt controller while kernel > > > > > is handling an IRQ. So any new interrupt generated before the kernel > > > > > handles the old interrupt will be lost. > > > > > > > > > I'm a little confused with your comment above. "INT lost while kernel > > > > processing the last INT". > > > > I would think it won't be lost, maybe more like delayed in processing. > > > > Doesn't the interrupt controller send the INT when the kernel re-enables the > > > > INT again. > > > > With what u are suggesting we would lose INT a lot. > > > > > > Here is an extract from the LDD3 sec 10.7: > > > > > > "void disable_irq(int irq); > > > void disable_irq_nosync(int irq); > > > void enable_irq(int irq); > > > > > > A driver can enable and disable interrupt reporting. If the hardware > > > tries to generate an interrupt while interrupts are disabled, the > > > interrupt is lost forever. A driver using a shared handler must not > > > use these functions." > > > > > > These are the functions that disable / enable irq at the PIC level. > > So do you mean, no interrupts are kind of buffered in the Local APIC > > while the APIC is waiting for EOI? > > If the interrupts are disabled at the APIC level (disable_irq()), then > no. If the interrupts are disabled at the processor > (local_irq_disable()), then yes. > > Somebody please CMIIW > > Thanks, > > Rajat _________________________________________________________________ Download Messenger. Start an i’m conversation. Support a cause. Join now. http://im.live.com/messenger/im/home/?source=TAGWL_MAY07 -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
