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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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