Messages in this thread | | | Date | Tue, 20 Feb 2001 00:02:48 +0100 | From | Ralf Baechle <> | Subject | Re: [help] _syscall2 fails with -fPIC |
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On Sat, Feb 17, 2001 at 11:47:09AM -0800, Mark Swanson wrote:
> I am building a -fPIC shared object that will define and access a Linux > kernel system call, but _syscall2 fails with -fPIC .so compilation. > What can I do? > > F.E. the statement: > > _syscall2 (int, tux, unsigned int, action, user_req_t *, req) > > Gives the following gcc error when compiled with -fPIC: > > tst.c: In function `tux': > tst.c:62: Invalid `asm' statement: > tst.c:62: fixed or forbidden register 3 (bx) was spilled for class > BREG. > > If the -fPIC isn't there it compiles fine. Unfortunately I need to find > another way as I have to use -fPIC.
Don't use the syscallX macros whenever possible; there are all sorts of portability problems hidden there. Their primary use is for within the kernel; any other use should be considered problematic. The prefered solution is putting the necessary stubs into libc; if that doesn't seem to be an option in your case try using the syscall() function defined in <unistd.h> like:
#include <sys/syscall.h> #include <unistd.h>
int main(char *argc, char *argv[]) { syscall(SYS_write, 1, "Hello, world\n", 13); }
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