Hi, Thanks for the suggestion but i am getting following error error: 'SYS_getrandom' undeclared (first use in this function) then i have replaced the SYS_getrandom by 275 in syscall(275, -- args--); as 275 is the __NR_getrandom defines in unistd.h file, but it is returning -1. Can somebody tell me what i am missing here?? . Also in /proc/kallsyms it is showing two syscalls added for getrandom ffffffff80417a38 T SyS_getrandom ffffffff80417a38 T sys_getrandom On Sat, Jun 18, 2016 at 7:12 PM, Sayutin Dmitry <cdkrot@xxxxxxxxx> wrote: > Well, in fact it is not hard. > > Just use syscall(2) provided by libc. > > You need to provide to this function syscall id and syscall args. > Syscall id can be retrieved from macro constant > Should look something like: > > #define _GNU_SOURCE > #include <unistd.h> > #include <sys/syscall.h> > > syscall(SYS_getrandom, -- your - args - here --); > > It returns long value - the result of syscall. > If it is between [-4095; -1] then it is negated errno, otherways it is return value. > > > 18.06.2016, 16:32, "Anoop" <anoop.chargotra@xxxxxxxxx>: >> Hi Avantika, >> >> On Sat, Jun 18, 2016 at 5:32 PM, Avantika Rawat <avani.rawat@xxxxxxxxx> wrote: >>> Hi ALL, >>> >>> I am trying to use getrandom syscall in kernel 3.10.20 by following this >>> link >>> >>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c6e9d6f38894798696f23c8084ca7edbf16ee895 >>> >>> i have compiled the kernel and now want to call the getrandom syscall from >>> userspace to generate random numbers. But i am getting following error while >>> calling the getrandom () from userspace. >>> >>> (.text.startup+0x18): undefined reference to `getrandom' >>> (.text.startup+0x1c): undefined reference to `getrandom' >> >> Your user space program will not know where 'getrandom' is defined >> unless it's in the C library. You need to research more on how to call >> custom system calls. >> >> -Anoop >> >>> -- >>> Regards, >>> Avantika Rawat >>> >>> _______________________________________________ >>> Kernelnewbies mailing list >>> Kernelnewbies@xxxxxxxxxxxxxxxxx >>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies@xxxxxxxxxxxxxxxxx >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > ----- > Sayutin Dmitry <cdkrot@xxxxxxxxxx> -- Regards, Avantika Rawat _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
