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    SubjectRe: [PATCH 3/5] parisc: use new macros for .data.init_task.
    On Sat, May 02, 2009 at 07:13:37AM +0200, Helge Deller wrote:
    > Tim Abbott wrote:
    > > .data.init_task should not need a separate output section; this change
    > > moves it into the .data section.
    > >
    > > Signed-off-by: Tim Abbott <tabbott@mit.edu>
    > > Cc: Kyle McMartin <kyle@mcmartin.ca>
    > > Cc: Helge Deller <deller@gmx.de>
    > > Cc: linux-parisc@vger.kernel.org
    >
    >
    > I think this patch is wrong, although it is theoretically correct.
    >
    > IIRC, gcc on hppa is not able to provide an alignment >= 8k, which is
    > why we have done the 16k alignment inside the linker script.
    > So, I think this change will prevent the parisc kernel to boot up.
    > Needs testing.

    The patch does not do much...

    >
    > Helge
    >
    > > ---
    > > arch/parisc/kernel/init_task.c | 2 +-
    > > arch/parisc/kernel/vmlinux.lds.S | 10 ++--------
    > > 2 files changed, 3 insertions(+), 9 deletions(-)
    > >
    > > diff --git a/arch/parisc/kernel/init_task.c b/arch/parisc/kernel/init_task.c
    > > index 1e25a45..8ee17ea 100644
    > > --- a/arch/parisc/kernel/init_task.c
    > > +++ b/arch/parisc/kernel/init_task.c
    > > @@ -48,7 +48,7 @@ EXPORT_SYMBOL(init_mm);
    > > * "init_task" linker map entry..
    > > */
    > > union thread_union init_thread_union
    > > - __attribute__((aligned(128))) __attribute__((__section__(".data.init_task"))) =
    > > + __attribute__((aligned(128))) __init_task_data =
    > > { INIT_THREAD_INFO(init_task) };
    This is a simple replacement with a nicer way to say "this belongs to
    the .data.init_task section - no functional difference.


    > >
    > > #if PT_NLEVELS == 3
    > > diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
    > > index b5936c9..c8a528d 100644
    > > --- a/arch/parisc/kernel/vmlinux.lds.S
    > > +++ b/arch/parisc/kernel/vmlinux.lds.S
    > > @@ -103,6 +103,8 @@ SECTIONS
    > > . = ALIGN(L1_CACHE_BYTES);
    > > /* Data */
    > > .data : {
    > > + /* assembler code expects init_task to be 16k aligned */
    > > + INIT_TASK_DATA(16384)
    > > NOSAVE_DATA
    > > CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES)
    > > DATA_DATA
    > > @@ -133,14 +135,6 @@ SECTIONS
    > > }
    > > __bss_stop = .;
    > >
    > > -
    > > - /* assembler code expects init_task to be 16k aligned */
    > > - . = ALIGN(16384);
    > > - /* init_task */
    > > - .data.init_task : {
    > > - *(.data.init_task)
    > > - }
    > > -
    This part moves away from a specific output section to including this in the
    .data output section - with the _same_ alignmnet.
    So the only issue here is that we move init_task before NOSAVE_DATA etc.

    I do not see why you think this changes alignmnet?

    Sam


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