Hello guys,
I am facing some issue during adding system call on OpenBSD 6.3. I
have shown my pathways to add system call, please guys correct me if
somewhere I have forgotten something to add or build.
1) echo "331 { int sys_hello(void); }" >> /usr/src/sys/kern/syscalls.master
2) make init_sysent.c
3) Add this file in /usr/src/sys/kern/sys_hello.c
#include <sys/types.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/syscallargs.h>
int
sys_hello(struct proc *p, void *v, register_t *retval)
{
printf("Hello world from kernel space.\n");
return (0);
}
4) echo "file kern/sys_hello.c" >> /usr/src/sys/conf/files
5) cd /usr/src/sys/arch/amd64/compile/CUSTOM.MP/
6) make obj && make -j4
And, then, It throws an error given below,
ld -T ld.script -X --warn-common -nopie -o bsd ${SYSTEM_HEAD} vers.o ${OBJS}
init_sysent.o 🙁.data+0x14b8): undefined reference to `sys_hello'
*** Error 1 in /usr/src/sys/arch/amd64/compile/CUSTOM.MP (Makefile:918
'bsd': @echo ld -T ld.script -X --warn-common -nopie -o bsd
'${SYSTEM...)
I have even tried to "make" with "-n" and "-d"options, so, that I can
debug make process, but, it didn't help me.
I have also tried to manually include sys.hello.o in {OBJS} in file
"/usr/src/sys/arch/amd64/compile/CUSTOM.MP/obj/Makefile" and also in
{CFILES} etc. like all other system calls files included. For example,
sys_generic.c etc.
But, some days ago, I did the same with OpenBSD 6.2 or 6.3 (I forgot)
in VirtualBox and it was working at that time.
The system call was added successfully at that time.
Alternative approach:
But, instead of adding a file for code of system call, I write "int sys_hello()" function inside sys_generic.c, like, sys_write() or sys_read() then there is no problem, I mean everything is compiled successfully and after booting into new kernel. I have used my implemented new system call.
Here, you guys can find link for my question in tech@openbsd.org
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