Dynamic pcpu, arm, mips, powerpc, sun, etc. help needed (fwd)
Jeff Roberson
jroberson at jroberson.net
Thu Jun 4 07:12:45 UTC 2009
Hi Folks,
I'm forwarding this in case you don't see it. Please help test and
implement the remaining change to machdep.c
Thanks,
Jeff
---------- Forwarded message ----------
Date: Wed, 3 Jun 2009 20:55:39 -1000 (HST)
From: Jeff Roberson <jroberson at jroberson.net>
To: arch at freebsd.org
Subject: Dynamic pcpu, arm, mips, powerpc, sun, etc. help needed
http://people.freebsd.org/~jeff/dpcpu.diff
This patch implements dynamic per-cpu areas such that kernel code can do the
following in a header:
DPCPU_DECLARE(uint64_t, foo);
and this in source:
DPCPU_DEFINE(uint64_t, foo) = 10;
local = DPCPU_GET(foo);
DPCPU_SET(foo, 11);
The dynamic per-cpu area of non-local cpus is accessable via
DPCPU_ID_{GET,SET,PTR}.
If you provide an initializer as I used above that will be the default value
when all cpus come up. Otherwise it defaults to zero. This is presently
slightly more expensive than PCPU but much more flexible. Things like id and
curthread should stay in PCPU forever.
I had to change the pcpu_init() call on every architecture to pass in storage
for the dynamic area. I didn't change the following three calls because it
wasn't immediately obvious how to allocate the memory:
./powerpc/booke/machdep.c: pcpu_init(pc, 0, sizeof(struct pcpu));
./mips/mips/machdep.c: pcpu_init(&__pcpu[0], 0, sizeof(struct pcpu));
./mips/mips/machdep.c: pcpu_init(pcpup, 0, sizeof(struct pcpu));
I have not tested anything other than amd64. If you have a !amd64
architecture, in particular any of the embedded architectures, I would really
appreciate it. Some of the arm boards postincrement the end address to
allocate early memory and some pre-decriment. Hopefully I got it right.
Thanks,
Jeff
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