Sir,<br><br><div class="gmail_quote">On Tue, Feb 15, 2011 at 4:16 PM, Mulyadi Santosa <span dir="ltr"><<a href="mailto:mulyadi.santosa@gmail.com">mulyadi.santosa@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hi... :)<br>
<div class="im"><br>
On Tue, Feb 15, 2011 at 16:08, Darshan Ghumare<br>
<<a href="mailto:darshan.ghumare@gmail.com">darshan.ghumare@gmail.com</a>> wrote:<br>
> Sir,<br>
> On x86 UP (Single CPU), Can lower priority (say) IRQ5 preempt higher one<br>
> (say) IRQ4 (Currently, CPU is executing interrupt handler of IRQ4)?<br>
<br>
</div>In Linux kernel, I never heard such irq prioritizing. Linux kernel<br>
does general preemption such that any code path could preempt other<br>
code path as long as preemption is allowed at that point and/or<br>
interrupt is enabled (which one affect the situation depends on type<br>
of code path).<br></blockquote><div> </div><div>IMHO, When the Processor is executing interrupt handler of IRQ4 then Processor is the one which pushes SS, SP, EFLAGS, CS & EIP on stack (in this case this will all corresponds to interrupt handler of IRQ4) & loads CS & EIP corresponding to IRQ5.</div>
<div>So, how come its depends on OS (kernel)? Please correct me if I am wrong.</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<br>
But, vaguely I read that Windows kernel does that.... that's why in<br>
certain BSOD you read message prefixed with "IRQL xxx xxx xxxx". That<br>
means lower interrupt handler somehow preempt higher one and that's<br>
not allowed.<br>
<br>
It comes from my raw observation so things might be wrong somewhere...<br>
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--<br>
regards,<br>
<br>
Mulyadi Santosa<br>
Freelance Linux trainer and consultant<br>
<br>
blog: <a href="http://the-hydra.blogspot.com" target="_blank">the-hydra.blogspot.com</a><br>
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