From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ewan Mellor <ewan@xensource.com>
Subject: Re: architecture-specific stuff in xend
Date: Wed, 9 Aug 2006 10:28:10 +0100
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	<20060808155953.GA20410@totally.trollied.org>
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To: John Levon <levon@movementarian.org>
Cc: xen-ppc-devel <xen-ppc-devel@lists.xensource.com>, xen-devel <xen-devel@lists.xensource.com>, Hollis Blanchard <hollisb@us.ibm.com>, xen-ia64-devel <xen-ia64-devel@lists.xensource.com>
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On Tue, Aug 08, 2006 at 04:59:53PM +0100, John Levon wrote:

> On Tue, Aug 08, 2006 at 10:34:25AM -0500, Hollis Blanchard wrote:
> 
> > Rather than having these inline tests everywhere ("if os.uname()[4] in
> > ('ia64', 'ppc64'):"), would it make more sense to have some sort of
> > "architecture" object, and do things like:
> 
> It'd be good if it were slightly more general and covered other system
> stuff too (namely OS). On Solaris some of the Xen binaries/scripts live
> in different locations in order to meet our file system requirements.
> 
> > I'm not sure how/where to instantiate the arch object though.
> 
> Presumably you could do the instance() singleton trick?

This being Python, you don't actually need singletons -- the containing module
is a singleton in its own right.  You can just write

Platform.py:

import os

if os.uname()[4] in ('ia64', 'ppc64'):
    def init_reservation(mem_kb):
        return something_else(mem_kb)

else:
    def init_reservation(mem_kb):
        return mem_kb

and then

import Platform
Platform.init_reservation(100)

will do the right thing.

Ewan.