Re: XFree 4.1
Lot of answers :-)
I have till now no time to take a look at the xserver sources, but I
downloaded the UserManual and programming manual of the 68060. And take a
look at the icache_flush makro.
So there are still some questions for me:
Alan: How do you flush the icache? I don't think that makro works =>
privileged instruction. And what is the difference to the 68060 and why?
And a general question: Why is it necesarry to flush the cache? I mean on my
machine sometimes it works sometimes not (I hate such errors) maybe it is
possible to do another workaraound? So where the icache has to be flushed
I hope I get some answers :-)
----- Original Message -----
From: Alan Hourihane <firstname.lastname@example.org>
To: Richard Zidlicky <email@example.com>
Cc: Kars de Jong <firstname.lastname@example.org>; Gerhard Täubl <email@example.com>;
Sent: Thursday, January 09, 2003 4:48 PM
Subject: 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
> > > 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.
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