On Wednesday 29 October 2008 14:10:33 loody wrote: > Dear all: > I try to build a kernel with -O and I try to modify below lines in > Makefile: > > ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE > KBUILD_CFLAGS += -O > else > KBUILD_CFLAGS += -O > endif With -O, the compiler tries to reduce code size and execution time, without performing any optimizations that take a great deal of compilation time. As to why this fails, I don't know. When I change my Makefile to reflect yours, and run a build with defconfig, It compiles without errors Which version are you using? (I use git head, e946217e4f) > > but the result will fail like below. > > calibrate.c:(.init.text+0x1338): undefined reference to > `__you_cannot_kmalloc_that_much' > init/built-in.o: In function `rd_load_image': > calibrate.c:(.init.text+0x1810): undefined reference to > `__you_cannot_kmalloc_that_much' > init/built-in.o: In function `crd_load': > calibrate.c:(.init.text+0x3da0): undefined reference to > `__you_cannot_kmalloc_that_much' > calibrate.c:(.init.text+0x3ef4): undefined reference to > `__you_cannot_kmalloc_that_much' > kernel/built-in.o: In function `call_usermodehelper_setup': > utsname_sysctl.c:(.text+0x15b38): undefined reference to > `__you_cannot_kmalloc_that_much' > kernel/built-in.o:utsname_sysctl.c:(.text+0x16c70): more undefined > references to `__you_cannot_kmalloc_that_much' follow > make[1]: *** [.tmp_vmlinux1] Error 1 > make[1]: Leaving directory `/mnt/hdb/uclinux/uClinux-dist/linux-2.6.x' > make: *** [linux] Error 1 this looks like a linker issue, or some unresolved .o files (do you include a .h file without building the objectfile?) > Is there any possibilities to build a kernel with -O version? > appreciate your help, yes, you can specify this in the menu Per default, you either optimize for size (general_setup -> optimize for size) -Os, or you optimze at -O2 > miloody > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx > Please read the FAQ at http://kernelnewbies.org/FAQ -- med Vennlig Hilsen - Yours Sincerely Henrik Austad
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