Re: [PATCH 4/4] powerpc: Allow LD_DEAD_CODE_DATA_ELIMINATION to be selected

Mathieu Malaterre
2018-04-20T20:08:49Z

On Fri, Apr 20, 2018 at 12:41 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
> On Fri, 20 Apr 2018 12:00:49 +0200
> Mathieu Malaterre <malat@debian.org> wrote:
>
>> On Fri, Apr 20, 2018 at 9:34 AM, Nicholas Piggin <npiggin@gmail.com> wrote:
>> > This requires further changes to linker script to KEEP some tables
>> > and wildcard compiler generated sections into the right place. This
>> > includes pp32 modifications from Christophe Leroy.
>> >
>> > When compiling powernv_defconfig with this option:
>> >
>> > text data bss dec filename
>> > 11827621 4810490 1341080 17979191 vmlinux
>> > 11752437 4598858 1338776 17690071 vmlinux.dcde
>> >
>> > Resulting kernel is almost 400kB smaller (and still boots).
>> >
>> > [ppc32 numbers here]
>>
>> ^^^
>>
>> Do you want somebody else to provide those numbers ?
>
> If you have a booting kernel, yes some more numbers would be good.

I've used /boot/config-4.15.0-2-powerpc from my current debian
package. Rebuild master with and without option, boot ok, load/unload
module ok.

$ size nick/vmlinux.with*
text data bss dec hex filename
7386425 2364370 1425432 11176227 aa8923 nick/vmlinux.with
7461457 2475122 1428064 11364643 ad6923 nick/vmlinux.without

This is not clear why with option the size of kernel is slightly bigger:

$ du -sk nick/vmlinux.with*
124488 nick/vmlinux.with
124004 nick/vmlinux.without

> Thanks,
> Nick