With built-in scsi disk driver, the final link fails with a following

error:

`.exit.text' referenced in section `.rodata' of drivers/built-in.o:

defined in discarded section `.exit.text' of drivers/built-in.o
This happens with -Os (CONFIG_CC_OPTIMIZE_FOR_SIZE=y) with all gcc-4

versions, and also with -O2 and gcc-4.3.
The problem is in sd.c:sd_major() being inlined into __exit function

exit_sd(), and the compiler generating a jump table in .rodata section

for the 'switch' statement in sd_major(). So we have references to

discarded section.
Fixed with a big hammer in the form of -fno-jump-tables.
Note that jump tables vs. discarded sections is a generic problem,

other architectures are just lucky not to suffer from it. But with

a slightly more complex switch/case statement it can be reproduced

on x86 as well. So maybe at some point we should consider

-fno-jump-tables as a generic compile option...
Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>

---

 arch/alpha/Makefile |    1 +

 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/alpha/Makefile b/arch/alpha/Makefile

index 4e1a8e2..4759fe7 100644

--- a/arch/alpha/Makefile

+++ b/arch/alpha/Makefile

@@ -13,6 +13,7 @@ NM := $(NM) -B

 LDFLAGS_vmlinux	:= -static -N #-relax

 CHECKFLAGS	+= -D__alpha__ -m64

 cflags-y	:= -pipe -mno-fp-regs -ffixed-8 -msmall-data

+cflags-y	+= $(call cc-option, -fno-jump-tables)
 cpuflags-$(CONFIG_ALPHA_EV4)		:= -mcpu=ev4

 cpuflags-$(CONFIG_ALPHA_EV5)		:= -mcpu=ev5

--

Most other architectures would only notice when the exit function

is called because they do late discardning og the exit section.

alpha (and sparc) are some of the few architectures that discard exit

section at link time thus you will see this much sooner

Are the any size penalties here?

I assume there are a minimal performance penalty.
	Sam

--

Just checked: quite the contrary, on alpha with -fno-jump-tables

resulting kernel image is a few kilobytes smaller (~17Kb in my config,
Yeah, I don't think there are lots of big switch statements in the

hot paths.
Ivan.

--