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Date:      Sun, 21 Jun 2009 16:03:12 +0200
From:      Marius Strobl <marius@alchemy.franken.de>
To:        Jeff Roberson <jroberson@jroberson.net>
Cc:        arch@freebsd.org, Peter Grehan <grehan@freebsd.org>
Subject:   Re: Dynamic pcpu, arm, mips, powerpc, sun, etc. help needed
Message-ID:  <20090621140312.GC71667@alchemy.franken.de>
In-Reply-To: <alpine.BSF.2.00.0906171231540.1025@desktop>
References:  <alpine.BSF.2.00.0906032050220.981@desktop> <20090609201127.GA50903@alchemy.franken.de> <4A2F1148.9090706@freebsd.org> <alpine.BSF.2.00.0906171231540.1025@desktop>

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On Wed, Jun 17, 2009 at 12:55:52PM -1000, Jeff Roberson wrote:
> 
> On Tue, 9 Jun 2009, Peter Grehan wrote:
> 
> >>As for sparc64 allocating the storage for the dynamic area
> >>from end probably isn't a good idea as the pmap code assumes
> >>that the range from KERNBASE to end is covered by the pages
> >>allocated by and locked into the TLB for the kernel by the
> >>loader
> >
> >Ditto for ppc. It's possible to get the additional space from within or 
> >after return from pmap_bootstrap() (like thread0's kstack, or the msgbuf).
> 
> http://people.freebsd.org/~jeff/dpcpu.diff
> 
> I have updated this patch based on feedback relating to various 
> architectures md code.  I tried to model most architectures after the way 
> msgbuf memory was taken.  I have no capacity to test anything other than 
> i386 and amd64.  ARM is reported to work with one minor diff.  Apparently 
> sparc64 worked with the earlier diff but this should be cleaner.  If 
> anyone can report back on sparc64, mips, or powerpc, I'd appreciate it.
> 

The earlier patch worked on sparc64 as long as the kernel
happened to leave enough room in the last 4MB page allocated
for it.
The new version unfortunately doesn't compile on sparc64 as
pmap_bootstrap_alloc() is static to its pmap.c (I think it
should also stay that way). Also the memory allocated with
it isn't safe to be used before we've taken over the trap
table. A kernel built with the sparc64 bits replaced with
the following patch boots fine:
http://people.freebsd.org/~marius/sparc64_dpcpu.diff
Do you have some simple test case for DPCPU which can be
used to verify that it actually works?

Marius




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