[Qemu-discuss] golang on linux-user

[Hunter Laux]

I was having trouble running golang on linux-user with an aarch64 target.

It turns out that snappy is written in Go. When I tried the xenial aarch64 preinstall image in qemu, Snappy was broken.

For some reason, it calls sigaction on all the signals.

I noticed do_sigaction in linux-user/signal.c calls the host sigaction. Unfortunately, glibc blocks signal 33 and for "SIGSETXID", which I guess is just a user signal that pthread names, but thats as far as I got into it.

See here:

https://sourceware.org/git/?p=glibc.git;a=blob;f=nptl/sigaction.c

Maybe there's some simple cleaner solutions, but here's what I did.

I made a quick fix by calling the __libc_sigaction instead of the __sigaction to bypass the check for SIGSETXID. It seems to work, but I'm not sure if that's safe. My "one liner" is definitely a hack.

After I did that, I kept getting an EXCP_YIELD. I'm not sure how to handle this, but ignoring it seems to work. Again, I'm not sure that's safe.

I can run snappy now, but if anyone has any comments on the patch below or better suggestions how to solve my problem let me know.

diff --git a/linux-user/main.c b/linux-user/main.c

index 700724e..c6fda61 100644

--- a/linux-user/main.c

+++ b/linux-user/main.c

@@ -1013,6 +1013,8 @@ void cpu_loop(CPUARMState *env)

         cpu_exec_end(cs);

 

         switch (trapnr) {

+        case EXCP_YIELD:

+            break;

         case EXCP_SWI:

             env->xregs[0] = do_syscall(env,

                                        env->xregs[8],

diff --git a/linux-user/signal.c b/linux-user/signal.c

index 962111c..08ca294 100644

--- a/linux-user/signal.c

+++ b/linux-user/signal.c

@@ -16,6 +16,8 @@

  *  You should have received a copy of the GNU General Public License

  *  along with this program; if not, see <http://www.gnu.org/licenses/>.

  */

+

+#define sigaction __libc_sigaction

 #include "qemu/osdep.h"

 #include <sys/ucontext.h>

 #include <sys/resource.h>

Thanks,

Hunter Laux