Re: bulk with i386 chroot on amd64? xen?

[is%netbsd.org@localhost]

Hi Greg,

On Tue, Aug 09, 2022 at 12:45:34PM -0400, Greg Troxel wrote:
> 
> This message is really about NetBSD, but I am interested in answers
> about other systems.
> 
> In thinking about bulk builds, I have a dim memory of two kinds of
> trouble, and I think some if not all of this memory is wrong :-)
> 
> I would like to ask if anyone is aware of any problems resulting from:
> 
>   2) building packages under xen and running them on not xen, or the
>   other way around.  In particular, i think this might be emacs and PAE
>   vs non-PAE.

Yes. Our XEN3PAE kernels offer a bigger address space to the userspace
processes than our i386 hardware kernels do. This results in an emacs
build which makes the resulting binary (memory is dim here:) try to load
its initialized data segment into the kernel's address space or to use
kernel's address space as userland, anyway - emacs crashes with SIGSEGV.

(For those not aware - i386 uses the top part of the address space
for the kernel, like the VAX (at least with VMS), which results in
easier kernel code to access user space, but smaller address space
for the user code.)

I had tried to play with the XEN kernel's parameters to make it use
the i386 addresses only, but must have overlooked something; what I
tried didn't work, and I built a i386 VM to build my i386 packages.

OTOH, i386-hardware (or i386-VM)-built emacs runs fine on a
XEN3PAE-kernel.

	-is