| Message ID | 234017be6d06ef84844583230542e31068fa3685.1676594211.git.falcon@tinylab.org (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | Add dead syscalls elimination support | expand |
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index e2b656043abf..8a73d7180cb8 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -103,6 +103,7 @@ config RISCV select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL select HAVE_KRETPROBES if !XIP_KERNEL select HAVE_RETHOOK if !XIP_KERNEL + select HAVE_LD_DEAD_CODE_DATA_ELIMINATION select HAVE_MOVE_PMD select HAVE_MOVE_PUD select HAVE_PCI diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S index 4e6c88aa4d87..51218cfe1ee4 100644 --- a/arch/riscv/kernel/vmlinux.lds.S +++ b/arch/riscv/kernel/vmlinux.lds.S @@ -101,7 +101,7 @@ SECTIONS . = ALIGN(8); .alternative : { __alt_start = .; - *(.alternative) + KEEP(*(.alternative)) __alt_end = .; } __init_end = .;
Select CONFIG_HAVE_LD_DEAD_CODE_DATA_ELIMINATION for RISC-V, allowing the user to enable dead code elimination. In order for this to work, ensure that we keep the alternative table by annotating them with KEEP. This boots well on qemu with both rv32_defconfig & rv64 defconfig, but it only shrinks their builds by ~1%, a smaller config is thereforce customized to test this feature: | rv32 | rv64 --------|------------------------|--------------------- No DCE | 4460684 | 4893488 DCE | 3986716 | 4376400 Shrink | 473968 (~10.6%) | 517088 (~10.5%) The config used above only reserves necessary options to boot on qemu with serial console, more like the size-critical embedded scenes: - rv64 config: https://pastebin.com/crz82T0s - rv32 config: rv64 config + 32-bit.config Signed-off-by: Zhangjin Wu <falcon@tinylab.org> --- arch/riscv/Kconfig | 1 + arch/riscv/kernel/vmlinux.lds.S | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-)