Re: [Linux-ia64] One little, two little, three little endian...

[Mario Smarduch <cms063@email.mot.com>]

David Mosberger wrote:

> Hi Gavin,
>
> >>>>> On Thu, 14 Nov 2002 16:52:13 -0800, "Gavin Scott" <gavin@allegro.com> said:
>
>   Gavin> Hello list, I want a big endian version of Linux for IPF.
>   Gavin> Just how crazy am I?
>
> Very! ;-)
>
> Seriously though: running big-endian processes is the easy part, the
> hard part is developing (& maintaining) big-endian versions of all
> libraries.  Not only is it a lot of work, but it would also fragment
> the ia64 linux market, so I'd consider it a Bad Thing (TM).
>
>   Gavin> Of course both MPE/iX and HP-UX are big-endian environments,
>   Gavin> and many of the people I talk to would be very interested in
>   Gavin> having an endian-compatible Linux that would run on big
>   Gavin> (i.e. IA-64) HP servers.  For this group, x86 compatibility
>   Gavin> is probably a non-issue.
>
> It would be a lot easier to add an hp-ux compatibility layer on top of
> ia64 linux.  The layer would emulate the (big-endian) hp-ux system
> calls and then you would install the big-endian hp-ux libraries on top
> of that (e.g., in the /emul/ia64-hpux/ tree).  Of course, I'm ignoring
> legal issues here as copying the hp-ux libraries would presumably
> require some sort of license.  But legal issues aside, this is doable
> and has been done many times before (e.g., alpha linux can run (some)
> Tru64 binaries, sparc linux can run sunos/solaris(?) binaries, etc.).

David a  quick question. Even though the library problem is overcomed,
how would signal handling be accomplished by an application
running in big-endian. Doesn't the kernel fill in the siginfo and context
while runing in little endian?

- Mario.

>
>
>   Gavin> I'm interested in any comments that come to mind.  I'm most
>   Gavin> interested in just how complex the task would be from a
>   Gavin> technical point of view, either to make the system buildable
>   Gavin> either way, or possibly supporting a per-process endian bit
>   Gavin> (which would be cool, but probably a lot more work).
>
> Actually, adding a per-process endian bit would be easy.  In fact,
> even without, a little-endian program can turn on the big-endian bit
> as long as it's prepared to deal with the consequences.  The hard part
> is really the libraries.
>
>         --david
>
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