Messages in this thread | | | Date | Wed, 30 Jun 2004 16:22:03 +0100 | From | Ian Molton <> | Subject | Re: A question about PROT_NONE on ARM and ARM26 |
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On Wed, 30 Jun 2004 15:59:42 +0100 Jamie Lokier <jamie@shareable.org> wrote:
> > Here's an optimisation idea, for ARM26 only: > ........................................... > > Do you need the "strlst" instructions in putuser.S? They're followed > by "strge" instructions.
ARM26 is special compared to some other architectures.
the CPU has a 64MB address space, and in all known ARM26 + MMU configurations, the bottom 32MB are the logical addresses. the upper 32MB (where kernel, physical RAM (16MB max) and IO live) are physically addressable ONLY.
the kernel isnt mapped into the virtual address space on ARM26. it could be, but with only 512 logical pages maximum on a normal machine (1024 on a machine with very little RAM) it would cripple the system even more than it already is.
the tests in ARM26 determine wether to use a translated access or a nontranslated one depending on wether we access kernel or user space. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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