Re: [Xen-devel] some thoughts on appstacks and app-tools

[Justin Cormack <justin@xxxxxxxxxxxxxxxxxxxxx>]

On Tue, Jul 15, 2014 at 4:26 PM, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:
>> 2) deciding if we want very simple "builtin" versions of some common
>> configuration utilities, or if we'll always include the full NetBSD
>> binaries
>
> Perhaps we can keep the set utilities small enough that we don't need
> to replicate busybox.

The problem about having a builtin set is that they are still big
enough to need tests and bugfixes and documentation and so on. If
NetBSD already had a Busybox it might be a different matter.

>> 3) deciding if we want applications themselves to handle backgrounding
>> e.g. via daemon(), or limit backgrounding to rc scripts using &, and
>> dealing with whatever problems arise as a result

Things like dhcp need to background, so need to resolve quite early on.

Something like crunchgen which creates an object file with a single
entry point that executes a single binary would be a nice outcome. But
it needs to deal with the memory allocation issues and globals. I
fudged up a hacky version in a rumprun branch somewhere but got rather
unhappy with it.

Another option that just occured to me, as performance of this setup
phase is not critical, might be to use a C interpreter eg
https://code.google.com/p/picoc/ to run the NetBSD utilities... That
then solves the namespacing issues, and allocation etc, obviously
needs hooking into the rump syscalls. Then you just ship (compressed)
source code in a config library. I might try prototyping this.

>> Of course, this whole mail isn't really specific to Xen, and I'd
>> eventually like to see things work the same way on all platforms.  But
>> we need at least one working platform as the first step ;)

Some platforms might have extra options, but Xen looks quite a bit
like many other environments I can think of. Userspace has similar
issues which I ran into trying to get some benchmarking code working,
when you dont use remote clients for performance reasons.

> Of course I appreciate that some of the xenstore-based answers I give
> above are perhaps less useful to other platforms, but perhaps they
> have something equivalent ?

Yes I think there is usually something roughly equivalent on most
platforms, although some might be somewhat simpler.

Justin

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