Attached patch gets build a bit further but then it fails due to not being Thumb ready:

 arm-linux-gnueabi-gcc -DHAVE_CONFIG_H -I. -I../../.. -g -I/home/hrw/devel/porting-jam/rtai-3.8.1/debian/linux/include -Wall -Wstrict-prototypes -pipe -D__IN_RTAI__ -D_GNU_SOURCE -fno-inline -I../../../base/include -I../../include -MT services.lo -MD -MP -MF .deps/services.Tpo -c services.c  -fPIC -DPIC -o .libs/services.o
In file included from ../../../base/include/asm/rtai.h:42:0,
                 from ../../../base/include/rtai.h:25,
                 from ../../../base/include/rtai_sched.h:22,
                 from ../../../base/include/rtai_lxrt.h:69,
                 from services.c:27:
../../../base/include/asm/rtai_hal.h:73:2: warning: #warning "by default, __LINUX_ARM_ARCH__ is setted to 4 in order to ensure compatibility with all other arm arch."
../../../base/include/asm/rtai_hal.h: In function '__rtai_generic_ulldiv':
../../../base/include/asm/rtai_hal.h:156:5: warning: implicit declaration of function 'do_div'
In file included from ../../../base/include/rtai_lxrt.h:579:0,
                 from services.c:27:
../../../base/include/asm/rtai_lxrt.h: In function '_rtai_lxrt':
../../../base/include/asm/rtai_lxrt.h:148:2: warning: #warning "RTAI_DO_SWI is not working yet. Please configure RTAI with --enable-lxrt-use-linux-syscall."
In file included from ../../../base/include/rtai_usi.h:26:0,
                 from ../../../base/include/rtai_tasklets.h:293,
                 from ../../../base/include/rtai_schedcore.h:39,
                 from services.c:29:
../../../base/include/asm/rtai_srq.h: In function 'rtai_srq':
../../../base/include/asm/rtai_srq.h:60:2: warning: #warning "RTAI_DO_SWI is not working yet. Please configure RTAI with --enable-lxrt-use-linux-syscall."
In file included from services.c:30:0:
../../../base/include/rtai_posix.h: In function 'internal_cond_cleanup':
../../../base/include/rtai_posix.h:1590:50: warning: value computed is not used
../../../base/include/rtai_posix.h: In function '__wrap_pthread_cond_wait':
../../../base/include/rtai_posix.h:1602:3: warning: value computed is not used
../../../base/include/rtai_posix.h: In function '__wrap_pthread_cond_timedwait':
../../../base/include/rtai_posix.h:1626:3: warning: value computed is not used
services.c: At top level:
../../../base/include/asm/rtai_hal.h:215:12: warning: '__rtai_generic_div96by32' is static but used in inline function '__rtai_generic_ullimd' which is not static
../../../base/include/asm/rtai_hal.h:178:12: warning: '__rtai_generic_ulldiv' is static but used in inline function '__rtai_generic_imuldiv' which is not static
{standard input}: Assembler messages:
{standard input}:8450: Error: instruction not allowed in IT block -- `str r5,[r7,#20]'
make[4]: *** [services.lo] Error 1
make[4]: Leaving directory `/home/hrw/devel/porting-jam/rtai-3.8.1/base/sched/liblxrt'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/home/hrw/devel/porting-jam/rtai-3.8.1/base/sched'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/home/hrw/devel/porting-jam/rtai-3.8.1/base'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/hrw/devel/porting-jam/rtai-3.8.1'
make: *** [all] Error 2