Messages in this thread | | | Date | Wed, 11 May 2011 08:52:53 +0800 | From | Lai Jiangshan <> | Subject | Re: 2.6.39-rc6-mmotm0506 and -next - __kfree_rcu breaks third-party kernel code |
| |
On 05/10/2011 12:56 AM, Valdis.Kletnieks@vt.edu wrote: > On Mon, 09 May 2011 09:17:57 PDT, Randy Dunlap said: > >> I'd be happy to see a simple fix, but we don't generally support building >> external modules without using the kernel kbuild infrastructure AFAIK -- >> and when I add a Makefile along with your kernconf.c file, it builds successfully >> on mmotm-2011-0506-1639. > > And in fact the module *does* use the Makefile stuff for the actual build - it > was just the installer's "am I looking at a sane 2.6 tree" sanity check that > bombed. So I go looking for what special sauce the Makefile adds to make it > work, and.... > > OK, *now* I'm confused. The magic sauce appears to be "-Os". Adding that makes > the compile work. And for no obvious reason - there's something in there that > causes indigestion, but only if the optimizer isn't invoked. > > *WTF*? > > LANG=C ./kern.sh > cat > /tmp/kernconf.c <<EOF > #include <linux/version.h> > #include <linux/utsname.h> > EOF > + cat > > kern="/lib/modules/2.6.39-rc6-mmotm0506/" > + kern=/lib/modules/2.6.39-rc6-mmotm0506/ > cc -D__KERNEL__ -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.6.0/include -I${kern}/build/include -I$kern/arch/x86/include/generated -include ${kern}/build/include/generated/autoconf.h -I${kern}/build/arch/x86/include -I${kern}/include/generated -Os -c /tmp/kernconf.c > + cc -D__KERNEL__ -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.6.0/include -I/lib/modules/2.6.39-rc6-mmotm0506//build/include -I/lib/modules/2.6.39-rc6-mmotm0506//arch/x86/include/generated -include /lib/modules/2.6.39-rc6-mmotm0506//build/include/generated/autoconf.h -I/lib/modules/2.6.39-rc6-mmotm0506//build/arch/x86/include -I/lib/modules/2.6.39-rc6-mmotm0506//include/generated -Os -c /tmp/kernconf.c > cc -D__KERNEL__ -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.6.0/include -I${kern}/build/include -I$kern/arch/x86/include/generated -include ${kern}/build/include/generated/autoconf.h -I${kern}/build/arch/x86/include -I${kern}/include/generated -c /tmp/kernconf.c > + cc -D__KERNEL__ -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.6.0/include -I/lib/modules/2.6.39-rc6-mmotm0506//build/include -I/lib/modules/2.6.39-rc6-mmotm0506//arch/x86/include/generated -include /lib/modules/2.6.39-rc6-mmotm0506//build/include/generated/autoconf.h -I/lib/modules/2.6.39-rc6-mmotm0506//build/arch/x86/include -I/lib/modules/2.6.39-rc6-mmotm0506//include/generated -c /tmp/kernconf.c > In file included from /lib/modules/2.6.39-rc6-mmotm0506//build/include/linux/sem.h:81:0, > from /lib/modules/2.6.39-rc6-mmotm0506//build/include/linux/sched.h:72, > from /lib/modules/2.6.39-rc6-mmotm0506//build/include/linux/utsname.h:35, > from /tmp/kernconf.c:2: > /lib/modules/2.6.39-rc6-mmotm0506//build/include/linux/rcupdate.h: In function '__kfree_rcu': > /lib/modules/2.6.39-rc6-mmotm0506//build/include/linux/rcupdate.h:822:2: error: size of unnamed array is negative > > rm /tmp/kernconf.c > + rm /tmp/kernconf.c > >
We use __always_inline for __Kfree_rcu(), we hope compiler does not compile it stand-alone, but it seems that __always_inline can't work without optimization, so you can add "-O2"(kernel build option) or "-Os" option for you third-party kernel modules' build.
| |