Re: [Tack-devel] ACK compiles on NetBSD-macppc, sort of...

[Perry E. M. <pe...@pi...>]

"Gregory T. (tim) Kelly" <gt...@di...> writes:
> At 4:13 PM -0400 7/21/06, Perry E. Metzger wrote:
>>>>Well, this is an assembler issue, right? It should be straightforward
>>>>to generate ELF instead of other formats. You pretty much *need* ELF
>>>>on all modern platforms -- Linux and all the rest use ELF too. You
>>>>probably also need to be able to properly embed debugging symbols...
>>>
>>> I can't answer that at this time.
>>
>>What is there to answer? :)
>
> Whether or not it is better to break the structure and generate ELF
> natively, or keep the ACK structure and convert ack.out to ELF.

In the end the two are equivalent provided you can pass directives
through all the way to the code that produces the ultimate ELF
executable.

>>> It is probably important to consider that Tanenbaum's group went
>>> with multiple address space segmentation for a virtual memory model,
>>> while the rest of the world went with singe address space paging.
>>
>>Er, huh????
>
> It would seem to me that the virtual memory model used by an
> operating system would have some impact on choices of file formats.

Not much.

>>All modern operating systems are
>>demand paged. There isn't even support for segmentation on PPC -- the
>>x86 alone of modern processors still sort of has it but it is a rather
>>lame holdover in the architecture.
>
> There's a difference between operating systems lacking support for
> PowerPC's segmentation model and PowerPC lacking support for
> segmentation.  While almost all operating systems lack support for
> PPC's segmentation model, PPC paged segmentation itself is quite
> robust (see Section 7.5 of the Programming Environment Manual, in
> particular the discussion on virtual segment IDs).

I stand partially corrected -- PPC has segments, but they are still
not segments in the old fashioned sense from the days when OSes
swapped entire processes in and out at once.

In any case, none of this makes any difference to whether you are
going to run on Linux or *BSD or anything else if you don't support
ELF.

Anyway, I'm bowing out of this discussion. I don't think I'm adding
anything any more.

Perry