Date: Fri, 09 Jul 2010 13:34:26 +0300 From: Andriy Gapon <avg@freebsd.org> To: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net>, freebsd-hackers@freebsd.org Cc: Konstantin Belousov <kib@freebsd.org>, Navdeep Parhar <np@freebsd.org>, Peter Wemm <peter@freebsd.org> Subject: Re: elf obj load: skip zero-sized sections early Message-ID: <4C36FB32.30901@freebsd.org> In-Reply-To: <4C343C68.8010302@freebsd.org> References: <4C246CD0.3020606@freebsd.org> <20100702082754.S14969@maildrop.int.zabbadoz.net> <4C320E6E.4040007@freebsd.org> <20100705171155.K14969@maildrop.int.zabbadoz.net> <4C321409.2070500@freebsd.org> <4C343C68.8010302@freebsd.org>
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Having thought and experimented more, I don't see why we need inline assembly at
all and why DPCPU_DEFINE can not simply be defined as follows:
#define DPCPU_DEFINE(t, n) \
t DPCPU_NAME(n) __section("set_pcpu") \
__aligned(CACHE_LINE_SIZE) __used
And, honestly, I can not understand the following comment in pcpu.h, although I
think I understand what's going on.
> /*
> * Define a set for pcpu data.
> *
> * We don't use SET_DECLARE because it defines the set as 'a' when we
Hmm, SET_DECLARE doesn't do anything like that.
Perhaps __MAKE_SET or one of its aliases was meant here?
> * want 'aw'. gcc considers uninitialized data in a separate section
> * writable, and there is no generic zero initializer that works for
> * structs and scalars.
> */
So, what's the problem here?
Don't we want that data to be considered writable? Haven't we just said that we
want "aw"? Don't we explicitly create a section with "aw" flags?
And why do we need a (universal) initializer? Why is it mentioned here at all?
Educate me. I demand it! :-)
--
Andriy Gapon
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