Hi:
I have a quwstion. Why the number 128 is reserver for system call exception in
interrupt vectors? Why not other numbers? Are there any historical reasons?
thanks.
--
Open WebMail Project (http://openwebmail.org)
2005/12/8, yen <[email protected]>:
> Hi:
> I have a quwstion. Why the number 128 is reserver for system call exception in
> interrupt vectors? Why not other numbers? Are there any historical reasons?
> thanks.
>
0x80 stands in the middle of [0..0xff].
--
Coywolf Qi Hunt
http://sosdg.org/~coywolf/
On Thu, 8 Dec 2005, Coywolf Qi Hunt wrote:
> 2005/12/8, yen <[email protected]>:
>> Hi:
>> I have a quwstion. Why the number 128 is reserver for system call exception in
>> interrupt vectors? Why not other numbers? Are there any historical reasons?
>> thanks.
>>
>
> 0x80 stands in the middle of [0..0xff].
> --
> Coywolf Qi Hunt
> http://sosdg.org/~coywolf/
If he's looking for 'secret codes' in the kernel, he might look
at:
LINUX_REBOOT_MAGIC2
LINUX_REBOOT_MAGIC2B
LINUX_REBOOT_MAGIC2C
... in linux-`uname -r`/include/linux/reboot.h Hint: Cvt dec to hex.
Cheers,
Dick Johnson
Penguin : Linux version 2.6.13.4 on an i686 machine (5589.55 BogoMips).
Warning : 98.36% of all statistics are fiction.
.
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Thank you.
yes, definetely a historical reason. System libraries need to know
this vector to invoke system call.
-Gaurav
On 12/8/05, yen <[email protected]> wrote:
> Hi:
> I have a quwstion. Why the number 128 is reserver for system call exception in
> interrupt vectors? Why not other numbers? Are there any historical reasons?
> thanks.
>
> --
> Open WebMail Project (http://openwebmail.org)
>
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--
- Gaurav
my blog: http://lkdp.blogspot.com/
--
On Sat, 2005-12-10 at 18:50 +0530, Gaurav Dhiman wrote:
> yes, definetely a historical reason. System libraries need to know
> this vector to invoke system call.
nowadays it's also mostly unused; sysenter and friends are used instead
and they don't use this entry point.
* Arjan van de Ven <[email protected]> wrote:
> On Sat, 2005-12-10 at 18:50 +0530, Gaurav Dhiman wrote:
> > yes, definetely a historical reason. System libraries need to know
> > this vector to invoke system call.
>
> nowadays it's also mostly unused; sysenter and friends are used
> instead and they don't use this entry point.
note that some system-calls are still invoked via int80 by glibc, such
as fork() - even on sysenter/syscall capable CPUs.
Ingo
>> On Sat, 2005-12-10 at 18:50 +0530, Gaurav Dhiman wrote:
>> > yes, definetely a historical reason. System libraries need to know
>> > this vector to invoke system call.
>>
>> nowadays it's also mostly unused; sysenter and friends are used
>> instead and they don't use this entry point.
>
>note that some system-calls are still invoked via int80 by glibc, such
>as fork() - even on sysenter/syscall capable CPUs.
OT: Any idea when glibc moves to use sysenter on capable CPUs?
Jan Engelhardt
--
On Thu, 2005-12-15 at 23:50 +0100, Jan Engelhardt wrote:
> >> On Sat, 2005-12-10 at 18:50 +0530, Gaurav Dhiman wrote:
> >> > yes, definetely a historical reason. System libraries need to know
> >> > this vector to invoke system call.
> >>
> >> nowadays it's also mostly unused; sysenter and friends are used
> >> instead and they don't use this entry point.
> >
> >note that some system-calls are still invoked via int80 by glibc, such
> >as fork() - even on sysenter/syscall capable CPUs.
>
> OT: Any idea when glibc moves to use sysenter on capable CPUs?
it has been doing that for a LOOOONG time
exception are syscalls that sysenter can't do (iirc 6 argument ones, and
I suspect fork() because it's just "special", but all normal ones are
done via sysenter already from even before 2.6.0 got released.