Messages in this thread | | | Date | Sat, 1 May 1999 03:25:13 -0700 | From | David Miller <> | Subject | Re: 64bit port |
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Date: Sat, 01 May 1999 03:05:51 -0700 From: "H. Peter Anvin" <hpa@transmeta.com>
I don't know what you mean with "medium-low code model"; I guess if it was up to me I'd say to heck with it, and waste 1/4294967296 of the address space as a 4 GB "null pointer check region"...
I presume the only reason you want that is to run 32-bit code/64-bit data or something like that (shades of DOS.)
It's an important code model which will satisfy the needs of %99 of all applications, it puts all code and data of the executable in the low 32-bits of the address space. It allows all function calls done within the executable to be a single instruction, and all address formation to be done in 2 instructions for all objects within the executable... the 64-bit types are the same etc.
We compile the sparc64 Linux kernel itself using this code model for those advantages. We used to use the medium-med code model (low 44-bit address space) and the difference in the generated code is phenominal.
Later, David S. Miller davem@redhat.com
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