Mailinglist Archive: opensuse (5130 mails)

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Re: [SLE] SUSE Linux 10.1 - 32-bit or 64-bit
  • From: Jerry Feldman <gaf@xxxxxxx>
  • Date: Mon, 15 May 2006 15:53:23 -0400
  • Message-id: <200605151553.23246.gaf@xxxxxxx>
On Monday 15 May 2006 2:46 pm, Bryan J. Smith wrote:
> This is introduced in pages 4-5 of Volume 2 "System Programming":
> http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/2
>4593.pdf
>
> Page 5 moves from talking about the legacy PAE to the use of a new,
> 52-bit PAE mode for Long Mode. It continues through page 13 of how a
> _kernel_ can support programs and libraries of any existing memory
> model.
> AMD (as well as Intel for that matter) do _not_ even attempt to tell OS'
> how to solve the issue of larger issue of programs and libraries of
> different memory models using each other's values or calling each
> other's routines in _any_ of its (nor Intel's) manuals.
Thanks for the reference. I had been using Volume 1 or the programmer's
manual since it deals with the actual instructions. I don't see anywhere in
Vol. I where PAE is mentioned.

The processor vendor (AMD/Intel/...) should not really get into telling an
OS how to interoperate the multiple memory models.
Note that a process only sees virtual memory and the specific registers of
its memory model. 32-bit programs effectively think they are on x86-32.

Maintaining multiple libraries has been around the Unix world for a very
long time where some vendors maintained 16-bit and 32-bit libraries.

Tru64 Unix on the Alpha only supported 64-bit addressing (and yes its
physical address space was architecturally limited to 48 bits). A special
32-bit compilation mode (TASO) allowed a 32-bit program to be built.

The bottom line with the 64-bit X86 architecture is that a 64-bit operating
system running in long mode can enable native 64-bit and 32-bit
applications to operate.

And for terminology purposes, the AMD64 implements 16 64-bit registers with
64-bit virtual addressing. the PAE-52 comes into play with physical
addressing.
--
Jerry Feldman <gaf@xxxxxxx>
Boston Linux and Unix user group
http://www.blu.org PGP key id:C5061EA9
PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

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