Re: int 0x40

[Brian Gerst]

Raman S wrote:
> 
> Hi,
>   I relatively new to the kernel and am trying to understand how the linux
> kernel handles interrupts. For this I attempted to
> create an int 0x40 by adding a set_system_gate(64, &system_call) in traps.c.
> I verfied by giving out print statements within set_system_gate that 64 is
> being set during initialization (though it isnt a surprise that it is being
> set).  But when i give an int 0x40 in a user level assembly program I get
> segmentation fault, (a SIGSEGV signal is sent to the process).  I have tried
> adding another function in entry.S called my_system_call and reproducing the
> code in system_call with a jmp ret_from_sys_call  at the end. Also tried
> giving an empty C function for my_system_call all with the same result.

The IRQ setup code is probably overwriting it.  You'll need to make the
code in i8259.c skip over vector 0x40 as well as SYSCALL_VECTOR (0x80).

--

				Brian Gerst