Re: use of setjmp/longjmp in x86 emulator.

From: Avi Kivity
Date: Sun Mar 07 2010 - 04:05:40 EST

On 03/02/2010 10:49 AM, Gleb Natapov wrote:
On Mon, Mar 01, 2010 at 02:56:59PM -0800, H. Peter Anvin wrote:
On 03/01/2010 02:31 PM, H. Peter Anvin wrote:
On 03/01/2010 11:18 AM, Zachary Amsden wrote:
It's going to be ugly to emulate segmentation, NX and write protect
support without hardware to do this checking for you, but it's just what
you have to do in this slow path - tedious, fully specified emulation.

Just because it's tedious doesn't mean we need to use setjmp / longjmp.
Throw / catch might be effective, but it's still pretty bizarre to do
tricks like that in C.

Well, setjmp/longjmp really is not much more than exception handling in C.

For what it's worth, I think that setjmp/longjmp is not anywhere near as
dangerous as people want to make it out to be. gcc will warn for
dangerous uses (and a lot of non-dangerous uses), but generally the
difficult problems can be dealt with by moving the setjmp-protected code
into a separate function.

Can I consider this as ACK for something like the patch blow? :) (with
proper x86 version of setjmp/longjmp of course).

The setjmp/longjmp implementation should definitely live in arch/*/lib, even if kvm is the only user.

error compiling committee.c: too many arguments to function

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