On 9/19/2010 4:49 AM, Sri Ram Vemulpali wrote:
Hi all,
This question is regarding Interrupt descriptor table. Why is the
IDTR 48-bits wide and
16Bit Limit + 32 bit Address = 48bits of IDTR.
why do we need limit field in the IDTR.
Because if we access beyond defined interrupt there will
be general protection fault.
Since we know there are 256 interrupts or exceptions possible, can't
we know boundary by deriving it by length of IDT field.
All interrupts are not always defined. There may be fewer
interrupts defined depending upon the requirements. Looking
up the 'limits' field is faster & less error prone than
find the length of the IDT, which i guess could only be
done via probing for all slots with has present flag set to 0.
Also, why is the IDT entry is 8 bytes long.
This 8 byte data structure is explained in intel's manual.
And how is the interrupt
line sharing is provided. Is sharing provided at OS code level.
I did not see any explanation of sharing at Intel manual (data sheet
of x86 system programming guide). Any thoughts.
Please clarify. Thanks.
--
Regards,
Sri.
Thanks.
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