RE: Seek Help !!! (about getting a pointer to sys_call_table)

["Dhiman, Gaurav" <Gaurav.Dhiman@xxxxxx>]

NO, IDTR contains the virtual address of IDT, it also contains the
length of IDT in number of bytes.

Cheers !!
Gaurav


-----Original Message-----
From: Thekkedath, Gopakumar [mailto:Gopakumar.Thekkedath@xxxxxxx] 
Sent: Friday, October 01, 2004 9:32 AM
To: Dhiman, Gaurav; Ashish Mishra
Cc: Kenel Newbies
Subject: RE: Seek Help !!! (about getting a pointer to sys_call_table)



>1. - get the pointer to IDT (Interrupt Descriptor Table), using SIDT
>assembly instruction. This instruction will store the value of IDTR
>register of processor, which actually is a pointer to IDT in kernel.

>2. - Once you get the pointer to IDT, get to the 128th entry of IDT by
>multiplying 128 with 8 (as each entry in IDT is of 8 bytes) and adding
>that to the IDT pointer, which we got in first step. This is a pointer
>to the system gate through with system calls enter kernel mode.

	Just a thought, the IDTR holds the physical address of the IDT
in
memory right? so to use that in the kernel,
u may have to convert it to virtual address.

gop



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