x86-64 on i386 (was Re: Promoting i386 version over x86_64?)

Paul Jakma paul at dishone.st
Thu Dec 17 09:13:15 UTC 2009

On Wed, 16 Dec 2009, Matthew Garrett wrote:

> The problem here is that you appear to be massively underestimating 
> the amount of work that would be required to actually support this 
> configuration.

Support is a multi-valued thing as well as a process. Not every i has 
to be dotted for something to be of use. E.g. there are secondary 
arches to act as staging grounds. I would not except everything to be 
magically perfect tomorrow, however there may be low-hanging fruit 
(like yum having separate notions of default native word-size for 
userspace and kernel, see below).

> We'd need to audit every ioctl entry point, every 
> file in proc and every sysfs attribute.

Or just let people file bugs as they find things..

> We'd need to port every application that uses vm86 over to using 
> x86emu.

Or let people using such apps continue to use a 32bit kernel (such 
kernel would have to continue to be supported, obv).

> We'd need to add, test and support a 32-to-64 bit cross building 
> toolchain.

GCC has a -m64 flag that may or may not help somewhat there (though, 
it got b0rken, though possibly just in combination with profiling).

> yum would need some amount of work that Seth has implied 
> is significant.

That's may be the easiest bit. It updates packages just fine, except 
it doesn't know I want it to install 64bit kernels, after I forced it 
to think the machine was 32bit.

> That's a lot of work for marginal benefits, and nobody seems 
> interested in stepping up to do that work.

I.e. money meet mouth, mouth likewise, you mean? :)

I'll try poke at it later in 2010. I'm more a C programmer than a 
python programmer, so I'd rather look at stuff like things like the 
SG_IO interface (which Peter Jones pointed me at in private) than at 
yum, but I'll see.

Paul Jakma	paul at jakma.org	Key ID: 64A2FF6A
One of the disadvantages of having children is that they eventually get old
enough to give you presents they make at school.
 		-- Robert Byrne

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