AcoSail/kernel_optimize_test
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sh: Enable skipping of bss on debug platforms for sh32 also.

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This enables the same functionality that sh64 has for sh32. When running
on simulated hardware or via remote memory via the debug interface,
memory is gauranteed to be zero on boot already, and skipping the zeroing
of BSS has measurable boot time benefits.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Paul Mundt 2008-12-17 15:33:43 +09:00
parent 8a655053ca
commit 740a3e677b
2 changed files with 22 additions and 5 deletions
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15
arch/sh/Kconfig.debug
View File

@ -98,6 +98,18 @@ config IRQSTACKS
for handling hard and soft interrupts. This can help avoid
overflowing the process kernel stacks.
config SH_NO_BSS_INIT
bool "Avoid zeroing BSS (to speed-up startup on suitable platforms)"
depends on DEBUG_KERNEL
default n
help
If running in painfully slow environments, such as an RTL
simulation or from remote memory via SHdebug, where the memory
can already be gauranteed to ber zeroed on boot, say Y.
For all other cases, say N. If this option seems perplexing, or
you aren't sure, say N.
config MORE_COMPILE_OPTIONS
bool "Add any additional compile options"
help
@ -125,9 +137,6 @@ config SH_ALPHANUMERIC
bool "Enable debug outputs to on-board alphanumeric display"
depends on SH_CAYMAN
config SH_NO_BSS_INIT
bool "Avoid zeroing BSS (to speed-up startup on suitable platforms)"
endif
endmenu

12
arch/sh/kernel/head_32.S
View File

@ -80,8 +80,14 @@ ENTRY(_stext)
mov.l 7f, r0
ldc r0, r7_bank ! ... and initial thread_info
#endif
! Clear BSS area
#ifndef CONFIG_SH_NO_BSS_INIT
/*
* Don't clear BSS if running on slow platforms such as an RTL simulation,
* remote memory via SHdebug link, etc. For these the memory can be guaranteed
* to be all zero on boot anyway.
*/
! Clear BSS area
#ifdef CONFIG_SMP
mov.l 3f, r0
cmp/eq #0, r0 ! skip clear if set to zero
@ -97,6 +103,8 @@ ENTRY(_stext)
mov.l r0,@-r2
10:
#endif
! Additional CPU initialization
mov.l 6f, r0
jsr @r0