2008/10/30 loody <miloody@xxxxxxxxx>: > 2008/10/29 Henrik Austad <henrik@xxxxxxxxx>: >> 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 >> Hi: I use gcc to compile normal linux kernel and it really works as you mentioned. I check where my problem come from. the compile complain he cannot find the function call, "__you_cannot_kmalloc_that_much." as below: include/linux/slab_def.h:48: undefined reference to `__you_cannot_kmalloc_that_much' ...... I grep the kernel source code, no matter normal linux or uclinux I download, there is no definition of function call "__you_cannot_kmalloc_that_much" in them. (below are the results I get: /media/sda6/uclinux/uClinux-dist/linux-2.6.x$ find . -type f -iname '*.[ch]' | xargs grep -n '__you_cannot_kmalloc_that_much' ./include/linux/slab_def.h:47: extern void __you_cannot_kmalloc_that_much(void); ./include/linux/slab_def.h:48: __you_cannot_kmalloc_that_much(); ./include/linux/slab_def.h:81: extern void __you_cannot_kmalloc_that_much(void); ./include/linux/slab_def.h:82: __you_cannot_kmalloc_that_much(); /media/sda6/uclinux/uClinux-dist/linux-2.6.x$ [root@localhost linux-2.6.16.2]# find . -type f -iname '*.[ch]' | xargs grep -n '__you_cannot_kmalloc_that_much' ./include/linux/slab.h:100: extern void __you_cannot_kmalloc_that_much(void); ./include/linux/slab.h:101: __you_cannot_kmalloc_that_much(); [root@localhost linux-2.6.16.2]# This makes me more curious about this problem. In the beginning, I thought maybe uclinux change some prototype to meet his requirement, since the .h file in uclinux called slab_def.h instead of slab.h in normal kernel. But I find both of them don't define the function. I know the unoptimized kernel is pretty big and useless under practical situation but I want to trace assembly code of kernel and the optimization will make me confuse. Would someone have the problem before or find I lost something to set, please let me know. appreciate your kind help, miloody -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
