lkml.org 
[lkml]   [2018]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] powerpc: Allow selection of CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
From
Date


Le 17/04/2018 à 18:45, Mathieu Malaterre a écrit :
> On Tue, Apr 17, 2018 at 12:49 PM, Christophe Leroy
> <christophe.leroy@c-s.fr> wrote:
>> This option does dead code and data elimination with the linker by
>> compiling with -ffunction-sections -fdata-sections and linking with
>> --gc-sections.
>>
>> By selecting this option on mpc885_ads_defconfig,
>> vmlinux LOAD segment size gets reduced by 10%
>>
>> Program Header before the patch:
>> LOAD off 0x00010000 vaddr 0xc0000000 paddr 0x00000000 align 2**16
>> filesz 0x0036eda4 memsz 0x0038de04 flags rwx
>>
>> Program Header after the patch:
>> LOAD off 0x00010000 vaddr 0xc0000000 paddr 0x00000000 align 2**16
>> filesz 0x00316da4 memsz 0x00334268 flags rwx
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>> arch/powerpc/Kconfig | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index 8fe4353be5e3..e1fac49cf465 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -888,6 +888,14 @@ config PPC_MEM_KEYS
>>
>> If unsure, say y.
>>
>> +config PPC_UNUSED_ELIMINATION
>> + bool "Eliminate unused functions and data from vmlinux"
>> + default n
>> + select LD_DEAD_CODE_DATA_ELIMINATION
>> + help
>> + Select this to do dead code and data elimination with the linker
>> + by compiling with -ffunction-sections -fdata-sections and linking
>> + with --gc-sections.
>> endmenu
>>
>
> Just for reference, I cannot boot my Mac Mini G4 anymore (yaboot). The
> messages I can see (prom_init) are:

Which version of GCC do you use ?

Can you provide the generated System.map with and without that option
active ?

Thanks
Christophe

>
> ---
> done
> copying OF device tree...
> Building dt strings...
> Building dt structure...
> Device tree strings 0x01100000 -> 0x01100e02
> Device tree struct 0x01101000 -> 0x01109000
> Quiescing Open Firmware ...
> Booting Linux via __start() @ 0x00140000 ...
> _
> ---
>
>
>
>> config ISA_DMA_API
>> --
>> 2.13.3
>>

\
 
 \ /
  Last update: 2018-04-17 18:50    [W:0.060 / U:0.276 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site