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To: David Gibson <david@gibson.dropbear.id.au>
Cc: Muli Ben-Yehuda <mulix@mulix.org>, Andrew Morton <akpm@osdl.org>,
       Anton Blanchard <anton@samba.org>, Adam Litke <agl@us.ibm.com>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       linux-kernel@vger.kernel.org, linuxppc64-dev@lists.linuxppc.org
Subject: Re: More convenient way to grab hugepage memory
References: <20040513055520.GF27403@zax> <20040513060549.GA12695@mulix.org>
	<20040513062014.GJ27403@zax>
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From: Roland Dreier <roland@topspin.com>
Date: 12 May 2004 23:45:57 -0700
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    David> Well, it's only called in one place - it's really the one
    David> function, just split up to let us put the wrapper creating
    David> the hugetlb file in the right place without excessive
    David> indentation.  I guess it doesn't really matter, with
    David> -funit-at-a-time it will end up the same anyway.

We seem to be in a strange situation with respect to -funit-at-a-time:

    arch/i386/Makefile:
    # Disable unit-at-a-time mode, it makes gcc use a lot more stack
    # due to the lack of sharing of stacklots.
    CFLAGS += $(call check_gcc,-fno-unit-at-a-time,)

    arch/x86_64/Makefile:
    # -funit-at-a-time shrinks the kernel .text considerably
    # unfortunately it makes reading oopses harder.
    CFLAGS += $(call check_gcc,-funit-at-a-time,)

    arch/ppc64/Makefile:
    # Enable unit-at-a-time mode when possible. It shrinks the
    # kernel considerably.
    CFLAGS += $(call check_gcc,-funit-at-a-time,)

It looks like i386/x86_64 led the way to -funit-at-a-time, ppc64
followed, and then i386 had second thoughts because of increased stack
usage around the time of 4K stacks.

No other archs have a position one way or another.

 -  Roland