From: Arnd Bergmann <[email protected]>
While experimenting with CONFIG_TRIM_UNUSED_KSYMS across architectures,
I noticed that this unsurprisingly works best when combined with the
--gc-sections linker flag, which is not currently allowed on m68k.
Enabling it with this patch shows significant improvements
for kernel size, looking at m68k defconfig with gcc-10, I get
4005135 1374302 167108 5546545 54a231 vmlinux-normal
3916254 1378078 167108 5461440 5355c0 vmlinux+trim
4012933 1362514 164280 5539727 54878f vmlinux+gcsection
3797884 1334194 164640 5296718 50d24e vmlinux+gcsection+trim
There are probably bugs somewhere, but if someone is able to test this
patch and fix any issues that come up, would be a useful improvement
for memory-limited machines.
Link: https://lore.kernel.org/lkml/CAK8P3a05VZ9hSKRzVTxTn+1nf9E+gqebJWTj6N23nfm+ELHt9A@mail.gmail.com/
Signed-off-by: Arnd Bergmann <[email protected]>
---
arch/m68k/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index c186733562b3..5f1aafa7b2e2 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -24,6 +24,7 @@ config M68K
select HAVE_DEBUG_BUGVERBOSE
select HAVE_FUTEX_CMPXCHG if MMU && FUTEX
select HAVE_IDE
+ select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
select HAVE_MOD_ARCH_SPECIFIC
select HAVE_UID16
select MMU_GATHER_NO_RANGE if MMU
--
2.29.2
Hi Arnd!
On 2/25/21 12:14 PM, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> While experimenting with CONFIG_TRIM_UNUSED_KSYMS across architectures,
> I noticed that this unsurprisingly works best when combined with the
> --gc-sections linker flag, which is not currently allowed on m68k.
>
> Enabling it with this patch shows significant improvements
> for kernel size, looking at m68k defconfig with gcc-10, I get
>
> 4005135 1374302 167108 5546545 54a231 vmlinux-normal
> 3916254 1378078 167108 5461440 5355c0 vmlinux+trim
> 4012933 1362514 164280 5539727 54878f vmlinux+gcsection
> 3797884 1334194 164640 5296718 50d24e vmlinux+gcsection+trim
>
> There are probably bugs somewhere, but if someone is able to test this
> patch and fix any issues that come up, would be a useful improvement
> for memory-limited machines.
Thanks, that sounds like a very helpful improvement. I'll test the patch next
week when I'm on vacation and report back if it works - unless someone beats
me to it ;-).
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer - [email protected]
`. `' Freie Universitaet Berlin - [email protected]
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
On Thu, Feb 25, 2021 at 12:14:45PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> While experimenting with CONFIG_TRIM_UNUSED_KSYMS across architectures,
> I noticed that this unsurprisingly works best when combined with the
> --gc-sections linker flag, which is not currently allowed on m68k.
>
> Enabling it with this patch shows significant improvements
> for kernel size, looking at m68k defconfig with gcc-10, I get
>
> 4005135 1374302 167108 5546545 54a231 vmlinux-normal
> 3916254 1378078 167108 5461440 5355c0 vmlinux+trim
> 4012933 1362514 164280 5539727 54878f vmlinux+gcsection
> 3797884 1334194 164640 5296718 50d24e vmlinux+gcsection+trim
>
> There are probably bugs somewhere, but if someone is able to test this
> patch and fix any issues that come up, would be a useful improvement
> for memory-limited machines.
>
> Link: https://lore.kernel.org/lkml/CAK8P3a05VZ9hSKRzVTxTn+1nf9E+gqebJWTj6N23nfm+ELHt9A@mail.gmail.com/
> Signed-off-by: Arnd Bergmann <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook