Re: amd64 kernel, i386 userland

[Michael <macallan%netbsd.org@localhost>]

Hello,

On Wed, 22 Jan 2014 00:24:52 +0200
Alan Barrett <apb%cequrux.com@localhost> wrote:

> On Tue, 21 Jan 2014, Emmanuel Dreyfus wrote:
> > In order to have more RAM without reinstalling everything, 
> > using an amd64 kernel on to of a i386 userland seems 
> > appealing. netbsd32 emulation works fine, and the machine boots 
> > to multiuser without a hassle.
> >
> > But there are minor problems, with binaries that use ioctl to 
> > talk with a kernel subsystem: I spoted ipf and raidctl.
> 
> If there are particular ioctls that don't have proper netbsd32 
> compat equivalents, they can be fixed on a case by case basis. 
> We'd need to start with a list of the problematic ioctls, either 
> by noticing what fails, or by systematically searching for ioctls 
> whose data includes fields that change size between 32-bit and 
> 64-bit systems.

I fixed a bunch of those when hacking on Loongson hardware ( 64bit MIPS
with 32bit userland ) - whatever X needs should be there.

> I think that we should also avoid adding such problematic kernel 
> interfaces in future, by using fixed width types wherever 
> possible.

Indeed.

have fun
Michael