[parisc-linux] depi?

[Alan Cox]

> Advantages of mapping the kernel at 0xc000 0000 (or 0x8000 0000/0xe000 0000)
> 
>  - consistent with what the other ports do / what hardware does for the other
>    ports (MIPS)

Not consistent with what some other ports do however. That one is a non
valid argument.

>  - clear difference between user pointers and kernel pointers (this matters
>    for debugging, not for a running system)

You can stick your elf binaries at 0x80000000 for debugging

>  - clear difference between physical addresses and kernel pointers.  Think
>    about vmalloc for one reason this is a good thing.  Also I dislike the
>    idea of staring at HPMCs for hours just to find out what really happened
>    is someone forgot to set the D bit and we didn't notice until we happened
>    to hit a vmalloc area.

Phys = Virt can help you. Ultrasparc makes good use of tlb bypass bits for
this.

>  - allows us to catch NULL pointers and use large pages to map the physical
>    memory [1]

Only relevant for debug. Indeed on x86 with 4Mb maps enabled we dont do 
null catches in the same way

>  - is already implemented

True

>  - conflicts with a rather obscure restriction of PA1.1 cache aliases.  As
>    Frank pointed out to me, it is only guaranteed you access the same data
>    using a physical address and a virtual address mapped to the physical if
>    the physical address is equal to the virtual address (or you are flushing
>    the cache lines in question).  I do not believe this to be a real problem
>    with any existing hardware and if it is, the performance hit of the
>    additional cache flushes may be seen as proper punishment for brain-dead
>    hardware.

The goal is to make it work well. X86 is brain dead, thats why we do the 
3gig/1gig game with it. 

Alan

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Subject: [hppa-linux] Initial HILO release.
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I've packaged Jason Eckhardt's HP bootloader, renamed it to 'HILO',
versioned it, and started on proper licensing.  This is teh first source
release, and it's clear that the source needs work.  I'll try to spend
some time on that next week.  We'll also put it into CVS.

In the mean time, here are the releases:

ftp://sod.res.cmu.edu/pub/parisc/hilo/hilo-0.01.gz (binary, precompiled)
ftp://sod.res.cmu.edu/pub/parisc/hilo/hilo-0.02.tar.gz (source)

The source does cross compile (with cross compilers I've not yet
released), I haven't tried native compiling yet.

- Alex

-- 
Alex deVries <puffin@redhat.com>     
Red Hat Contrib Net maintainer          
Ottawa, Canada  
HPPA/Linux Porting Team


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