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Jason Kraftcheck wrote:<br>
<blockquote type="cite" cite="mid40F2EDD7.6000808@facstaff.wisc.edu">
<pre wrap="">Joel Anderson wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Marc-David Meijer wrote:
As I understand it, PCI devices don't depend on IRQs anyway. They use
interrupt "channels", and IRQs are just kept around to keep legacy stuff
happy. You will often see many devices appear to "share" the same IRQ,
but it is not really true since IRQ's can't really _be_ shared.
Someone please comment if I haven't explained this correctly. It's a
simplification, but it basically means that IRQ issues shouldn't come
into play unless you have some legacy hardware in the system also.
</pre>
</blockquote>
<pre wrap=""><!---->
I'm no expert either, but I think they are actually "shared". The
interrupt handler must poll each device by invoking the interrupt
handler in the driver for each device sharing the interrupt. Thus
there's a slight performance loss when sharing interrupts, and also the
possibility for buggy drivers to interfere with each other.
</pre>
</blockquote>
Newer PCI devices support "Message Signalled Interrupts" which use no
physical IRQ line, but instead write a pre-configured value to the PCI
bridge inbound MSI register to cause a unique interrupt. I can't say
for sure the 250MCE actually does that (or that the driver sets it up
that way) but it is possible. People have commented eslwhere on the
list that it appears the 250MCE needs a PCI Rev 2.2 compliant
motherboard, so you might want to check your mobo docs out and see if
it complies.<br>
<br>
Tim<br>
<br>
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