Re: XFree 4.1
On Thu, Jan 09, 2003 at 03:37:16PM +0100, Richard Zidlicky wrote:
> On Wed, Jan 08, 2003 at 09:34:40PM +0000, Alan Hourihane wrote:
>
> > It's only the instruction cache we need to flush. Not the whole cache.
> > I notice in asm-m68k/pgalloc.h there's a specific flush_icache() macro
> > to do just that.
>
> all cacheflush instructions are priviliged. There is a little trick
> to force datacache flush without a syscall using the move16 insn, this
> would however work on 68040/060 only and doesn't solve the issue with
> the program cache.
>
> > There are only two relocations used in the loader for m68k at the moment,
> > and I doubt it's going to be a massive performance hit. But having a
> > working loader is a step in the right direction even if it is slower.
> > We can work out how to speed it up later.
>
> it is slow enough even without the loader. Every sort of relocation
> is likely to slow down program startup drastically, this is because
> the relocation does force a tremendeous lot of pages to be paged in
> just to fix the relocation address - in many cases those pages aren't
> ever touched again. Effectively this defeats demand paging, the
> additional cacheflush is just the tip of the iceberg and perhaps even
> irelevant compared to the time spent with paging.
>
> It would be certainly good to have the module loader, but for the
> average m68k user this is of no benefit and so I think m68k should
> default to statically linked Xserver.
Your loosing a lot of configurability without the loader.
If no one is interested here, I hope to get time to poke at this some
more. Unfortunately I only have a WarpEngine 4040 which nicely does
the cache flushing for me and so the loader works regardless for me.
Alan.
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