Re: [Qemu-discuss] s390x user-mode working example

[Alex Kashchenko]

On 11/24/2017 05:57 AM, Thomas Huth wrote:
> On 23.11.2017 22:00, Alex Kashchenko wrote:
> > Hi,
> >
> > I am trying to build qemu-s390x-user static binary to run a hello-world
> > program cross-compiled with gcc-s390x-linux-gnu on linux_x86_64.
> >
> > I am building qemu with:
> >
> > ./configure --static --disable-werror --target-list=s390x-linux-user
> > make
> >
> > and running example with:
> >
> > QEMU_STRACE=1 ./s390x-linux-user/qemu-s390x path/to/s390x-hello
> >
> > I tried latest git and a number of v2.x releases without success. Can
> > see either hang (on first brk call) or various errors for newer versions
> > and "Illegal instruction" for older ones. Tried on ubuntu 16.04 and
> > 17.10 without success.
> >
> > The same steps worked for me for ppc64le hello-world.
> >
> > Any help on this is highly appreciated.
>
> How did you cross-compile your s390x binary? QEMU's CPU emulation only
> fully supports the z900 so far (more support is being worked on), so you
> should make sure that your program has been compiled for that CPU
> architecture, i.e. add "-m64 -march=z900" to your CFLAGS. Does that help?

Thanks for suggestion! I was cross-compiling the example using 
s390x-linux-gnu-gcc without additional flags, but it seems that 
march=z900 is a default for this gcc build. I was able to run simple 
example successfully (with git master build) after deleting 
/etc/ld.so.cache .

My ultimate goal was to cross-compile OpenJDK for s390x and run it 
locally with QEMU-user to be able to smoke-test s390x OpenJDK builds for 
fedora (I am using ubuntu for experiments because of very convenient 
multiarch support in it).

Unfortunately, I just found that OpenJDK's JIT requires newer 
instruction set than z900:

$ ./s390x-linux-user/qemu-s390x 
~/jdk9/build/linux-s390x-normal-server-release/images/jdk/bin/java -version
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (vm_version_s390.hpp:367), pid=26037, tid=26039
#  guarantee((_features[0] & GnrlInstrExtFacilityMask) == 
GnrlInstrExtFacilityMask) failed: We no more support older than z10.
#
# JRE version:  (9.0) (build )
# Java VM: OpenJDK 64-Bit Server VM (9-internal+0-adhoc.u1804.jdk9, 
mixed mode, tiered, compressed oops, g1 gc, linux-s390x)

--
-Alex