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    SubjectRe: [PATCH 14/23] make section names compatible with -ffunction-sections -fdata-sections: parisc
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    On Wed, 2008-07-02 at 02:00 +0200, Denys Vlasenko wrote:
    > On Wednesday 02 July 2008 01:41, James Bottomley wrote:
    > > On Wed, 2008-07-02 at 02:39 +0200, Denys Vlasenko wrote:
    > > > The purpose of this patch is to make kernel buildable
    > > > with "gcc -ffunction-sections -fdata-sections".
    > > > This patch fixes parisc architecture.
    > > >
    > > > Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
    > >
    > > Um ... if you look at the Makefile you'll see we already build parisc
    > > with -ffunction-sections; we have to: our relative jumps are too small
    > > to guarantee finding the stubs in large files.
    > >
    > > Since our text is -ffunction-sections compatible already, I question the
    > > need for transformations like this:
    > >
    > > > - *(.text.do_softirq)
    > > > - *(.text.sys_exit)
    > > > - *(.text.do_sigaltstack)
    > > > - *(.text.do_fork)
    > > > + *(.do_softirq.text)
    > > > + *(.sys_exit.text)
    > > > + *(.do_sigaltstack.text)
    > > > + *(.do_fork.text)
    >
    > arch/parisc/kernel/vmlinux.lds.S contains these lines:
    >
    > TEXT_TEXT
    > SCHED_TEXT
    > LOCK_TEXT
    > *(.text.do_softirq)
    > *(.text.sys_exit)
    > *(.text.do_sigaltstack)
    > *(.text.do_fork)
    >
    > which suggested to me that for parisc it is important to have
    > these sections in that place (after LOCK_TEXT) and order.

    Yes ... moderately.

    > If you use -ffunction-sections, any function with the name
    > do_fork (say, a static function somewhere) will end up in
    > .text.do_fork function, and will be "mixed up" with
    > global do_fork(). For parisc it is maybe not a problem
    > (I am not an expert) but in other places/arches people
    > clearly would not want this kind of things to happen.

    Erm, but we're trying to name text sections of the -ffunction-sections.
    We're doing this because we are trying to do a semblance of a reasonable
    arrangement for the relative jumps (and avoid stubs). Your patch is
    explicitly breaking all of this.

    > In order to handle these situations uniformly, in these patches
    > I decided to _never_ use .text.XXXX names for sections,
    > effectively leaving them "reserved for gcc's use".

    We need to use the names gcc outputs, not some random name.

    > Did I understand you right that in this chunk I need to
    > leave .text.FUNC_NAME as it was before?

    Yes.

    > > And thus by the same token the data transformations.
    >
    > It would be easiest for me if you will reply to the parisc patch
    > and indicate all parts where I should NOT do name change.

    That would be the piece above.

    James




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