NASM interrupt x86 reference?

Question

I can't seem to find a good reference for NASM x86 interrupts on a Linux system. For example, what is int 0x60 and how is it different from int 0x80?

Is there a manual somewhere which will list all the interrupt numbers which can be used in conjunction with the int instruction?

+1 for the nostalgia... Below there are the breadcrumbs to home :-) — xanatos, Mar 13 '11 at 16:17
0x60 and 0x80 are numbers, and NASM has not a single thing in the world to do with it -- it doesn't do anything with those numbers besides copy them from the input to the output. — hobbs, Mar 13 '11 at 16:19
0x80 sounds like the syscall handler on various Linuxes. But as was mentioned, it depends on the system. int3 (separate instruction) on Windows is a break point into the debugger, for example. — 0xC0000022L, Mar 13 '11 at 16:19

score 5 · Accepted Answer · edited Sep 06 '21 at 06:14

5

Linux only uses int 0x80 (or sysenter or syscall), with a call number in EAX. Check unistd_32.h, and see

What are the calling conventions for UNIX & Linux system calls (and user-space functions) on i386 and x86-64
What happens if you use the 32-bit int 0x80 Linux ABI in 64-bit code?

For 16-bit x86, there's a long history of different interrupt numbers for different groups of interfaces, often with a call number in just AH.

There is the Ralph Brown's... It's soo many years...

http://www.ctyme.com/rbrown.htm

Instead of looking for a grain of sand in the desert, you could ask directions to Wiki:

BIOS

DOS

http://en.wikipedia.org/wiki/MS-DOS_API

edited Sep 06 '21 at 06:14

Peter Cordes

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answered Mar 13 '11 at 16:15

xanatos

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+1 - Overwhelming... but it seems like the info is there... somewhere. – Richard JP Le Guen Mar 13 '11 at 16:48
@Leguri Too much informations? :-) You asked for it :-) :-) Unless you need specific things, the BIOS and DOS Category should have everything you need. – xanatos Mar 13 '11 at 17:55
Indeed I did :) Unless a more... shall we say... concise answer pops up, the tick's yours. – Richard JP Le Guen Mar 13 '11 at 18:25
@LeguRi Good luck with your Real Mode DOS :-) – xanatos Mar 14 '11 at 18:22
The question asked about Linux, but this accepted answer didn't even mention it >.<. I updated with a couple relevant links for that, and added tags to the question that make it relevant for the BIOS answer. – Peter Cordes Sep 06 '21 at 06:16

score 3 · Answer 2 · edited Mar 14 '11 at 18:45

3

You can use any number from 1 to 255. Those are software generated interrupts

But the meaning/behaviour of it will pretty much depend on the operating system you are running it on! Or more exactly on the registered routine in the IDT that will handle that interrupt.

edited Mar 14 '11 at 18:45

Richard JP Le Guen

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answered Mar 13 '11 at 16:17

dreyercito

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Interrupt 0 is also valid to use. Interrupts 0 to 31 are used by the CPU for faults too, but 0 is no different from 1 regarding that. – ecm Mar 24 '20 at 14:11
Note that in protected mode, the `int 0` is different from actually triggering a `#DE` exception, e.g. via `div edx`. The IDT entries may not allow user-space to call into the exception handlers with `int`, especially `#PF`, only allow entry from triggering the faults "organically". – Peter Cordes Sep 06 '21 at 06:18

NASM interrupt x86 reference?

2 Answers2