Date: Wed, 23 Jun 2010 02:38:06 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: freebsd-hackers@freebsd.org Cc: freebsd-current@freebsd.org Subject: [HEADS UP] Kernel modules don't work properly in FreeBSD 8.1-RC1 Message-ID: <201006230238.06831.hselasky@c2i.net>
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Hi, I'm creating a new thread on this issue. On Tue, Jun 22, 2010 at 04:39:17PM -0400, Ryan Stone wrote: > I saw similar behaviour a couple of years ago when I switched from > using gcc 4.0.2 to gcc 4.3.0 to compile some out-of-tree KLD modules. > The problem ended up being a change in the linker script used by GNU > ld for linking kernel modules. It used to always put some magic > symbols used by the linker to implement things like sysinits into the > module. It was changed to only provide those symbols, which > apparently means that the linker would discard those symbols if > nothing referenced them(and nothing did reference them). I had to > work around it by adding the following to my link line: > > -u __start_set_sysinit_set -u __start_set_sysuninit_set \ > -u __start_set_sysctl_set -u __start_set_modmetadata_set \ > -u __stop_set_sysinit_set -u __stop_set_sysuninit_set \ > -u __stop_set_sysctl_set -u __stop_set_modmetadata_set It appears many kmods are broken because the linker is stripping away static data declared with the section attribute in FreeBSD 8.1-RC1. <cite> I added those lines to the LDFLAGS in Makefile.kmod in the cuse4bsd port made the module and the result loads and creates the /dev/cuse file. Here's a diff relative to /usr/ports/multimedia/cuse4bsd-kmod/work/cuse4bsd-kmod-0.1.11 just so it's clear what I did. --- Makefile.kmod.orig 2010-02-11 03:28:02.000000000 -0800 +++ Makefile.kmod 2010-06-22 14:02:52.000000000 -0700 @@ -30,4 +30,10 @@ KMOD= cuse4bsd SRCS= cuse4bsd_kmod.c device_if.h bus_if.h vnode_if.h +LDFLAGS += -u __start_set_sysinit_set -u __start_set_sysuninit_set \ + -u __start_set_sysctl_set -u __start_set_modmetadata_set \ + -u __stop_set_sysinit_set -u __stop_set_sysuninit_set \ + -u __stop_set_sysctl_set -u __stop_set_modmetadata_set + + .include <bsd.kmod.mk> Running nm -o on the two modules, the difference seems to be that the -u results in some additional absolute symbols being defined: Bad module: $ nm -o /boot/modules/cuse4bsd.ko| grep sys /boot/modules/cuse4bsd.ko:0000275c r __set_sysinit_set_sym_cuse_kern_init_sys_init /boot/modules/cuse4bsd.ko:00002758 r __set_sysuninit_set_sym_cuse_kern_uninit_sys_uninit /boot/modules/cuse4bsd.ko:00003194 d cuse_kern_init_sys_init /boot/modules/cuse4bsd.ko:00003184 d cuse_kern_uninit_sys_uninit Good module: $ nm -o ./cuse4bsd.ko | grep sys ./cuse4bsd.ko:000028cc r __set_sysinit_set_sym_cuse_kern_init_sys_init ./cuse4bsd.ko:000028c8 r __set_sysuninit_set_sym_cuse_kern_uninit_sys_uninit ./cuse4bsd.ko: U __start_set_sysctl_set ./cuse4bsd.ko:000028cc A __start_set_sysinit_set ./cuse4bsd.ko:000028c8 A __start_set_sysuninit_set ./cuse4bsd.ko: U __stop_set_sysctl_set ./cuse4bsd.ko:000028d0 A __stop_set_sysinit_set ./cuse4bsd.ko:000028cc A __stop_set_sysuninit_set ./cuse4bsd.ko:00003194 d cuse_kern_init_sys_init ./cuse4bsd.ko:00003184 d cuse_kern_uninit_sys_uninit </cite> --HPS
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