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+---
+layout: post
+title: "QEMU TCG Tests"
+date: 2018-06-21 10:30:00:00 +0000
+last_modified_at: 2018-06-21 10:30:00:00 +0000
+author: Alex Bennée
+categories: [testing, docker, compilation, tcg]
+---
+
+Ever since I started working on QEMU there was a small directory
+called tests/tcg that was in a perpetually broken state. It contains
+tests that exercise QEMU's ability to work across architectures using
+the power of the Tiny Code Generator. However as these tests needed to
+be compiled for the *guest* architectures and not the *host*
+architecture - known as cross-compiling - most developers never ran
+them. As the tests were hardly ever built inevitably a certain amount
+of bit-rot set in.
+
+# Cross Compilers
+
+In the old days cross-compilation setups were almost all hand-crafted
+affairs which involved building versions of binutils, gcc and a basic
+libc. If you couldn't get someone to give you a pre-built tarball it
+was something you laboured through once and hopefully never had to
+touch again. There were even dedicated scripts like crosstool-ng which
+attempted to make the process of patching and configuring your
+toolchain easier.
+
+While the distributions have improved their support for cross
+compilers over the years there are still plenty of variations in how
+they are deployed. It is hard for a project like QEMU which has to
+build on a wide range of operating systems and architectures to
+seamlessly use any given distributions compiler setup. However for
+those with cross compilers to hand `configure` now accepts two
+additional flags:
+
+ --cross-cc-$(ARCH)
+ --cross-cc-flags-$(ARCH)
+
+With a compiler specified for each guest architecture you want to test
+the build system can now build and run the tests. However for
+developers that don't have cross compilers around they can now take
+advantage of QEMU's docker images.
+
+# Enter Docker Containers
+
+If you work in IT you would be hard pressed not to have noticed the
+hype around Docker and the concept of containerisation over the last
+few years. Put simply containers allow you to define a known working
+set of software that gets run in an isolated environment for a given
+task. While this has many uses for QEMU it allows us to define build
+environments that any developer can run without having to mess around
+with their preferred host setup.
+
+Over the last few years QEMU's build system has been expanding the
+number of docker images it supports. Most of this has been in service
+of our CI testing such as [Patchew](https://patchew.org/QEMU/) and
+[Shippable](https://app.shippable.com/github/qemu/qemu/dashboard) but
+any developer with a docker setup can run the exact same images. For
+example if you want to check your patches won't break when compiled on
+a 32 bit ARM system you can run:
+
+ make docker-test-build@debian-armhf-cross J=n
+
+instead of tracking down a piece of ARM hardware to actually build on.
+Run `make docker` in your source tree to see the range of builds and
+tests it can support.
+
+# make check-tcg
+
+With the latest work [merged into
+master](https://git.qemu.org/?p=qemu.git;a=commit;h=TODO) we can now
+take advantage of both hand configured and docker based cross
+compilers to build test cases for TCG again. To run the TCG tests
+after you have built QEMU:
+
+ make check-tcg
+
+and the build system will build and run all the tests it can for your
+configured targets.
+
+# Rules for tests/tcg
+
+So now we have the infrastructure in place to add new tests what rules
+need to be followed to add new tests?
+
+Well the first thing to note is currently all the tests are for
+linux-user versions of QEMU. This means the tests are all currently
+user-space tests that have access to the Linux syscall ABI.
+
+Another thing to note is the tests are standalone from the rest of the
+QEMU test infrastructure. To keep things simple they are compiled as
+standalone "static" binaries. As the cross-compilation setup can be
+quite rudimentary for some of the rarer architectures we only compile
+against a standard libc. There is no support for linking to other
+libraries like for example glib. Thread and maths support is part of
+glibc so shouldn't be a problem.
+
+Finally when writing new tests consider if it really is architecture
+specific or can be added to `tests/tcg/multiarch`. The multiarch tests
+are re-built for every supported architecture and should be the
+default place for anything explicitly testing syscalls and other
+common parts of the code base.
+
+# What's Next
+
+My hope with this work is we can start adding more tests to
+systematically defend functionality in linux-user. In fact I hope the
+first port of call to reproducing a crash would be writing a test case
+that can be added to our growing library of tests.
+
+Another thing that needs sorting out is getting toolchains for all of
+the less common architectures. The current work relies heavily on the
+excellent work of the Debian toolchain team in making multiarch
+aware cross compilers available in their distribution. However QEMU
+supports a lot more architectures than QEMU, some only as system
+emulations. In principle supporting them is as easy as adding another
+docker recipe but it might be these recipes end up having to compile
+the compilers from source.
+
+The `tests/tcg` directory still contains a number of source files we
+don't build. Notably the cris, lm32, mips, openrisc and xtensa targets have
+a set of tests that need a system emulator. Now we have the
+infrastructure for compiling I hope we can get support for system
+tests added fairly quickly. There will need to be some work to figure
+out a nice common way to pass results back to the build-system. For
+linux-user this is simple as all programs can simply return their exit
+code however for system emulation this is a little more involved.
+
--
2.17.1
Hi, This series seems to have some coding style problems. See output below for more information: Type: series Message-id: 20180621184116.910-1-alex.bennee@linaro.org Subject: [Qemu-devel] [PATCH] blogposts: add post about the new check-tcg infrastructure === TEST SCRIPT BEGIN === #!/bin/bash BASE=base n=1 total=$(git log --oneline $BASE.. | wc -l) failed=0 git config --local diff.renamelimit 0 git config --local diff.renames True git config --local diff.algorithm histogram commits="$(git log --format=%H --reverse $BASE..)" for c in $commits; do echo "Checking PATCH $n/$total: $(git log -n 1 --format=%s $c)..." if ! git show $c --format=email | ./scripts/checkpatch.pl --mailback -; then failed=1 echo fi n=$((n+1)) done exit $failed === TEST SCRIPT END === Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384 From https://github.com/patchew-project/qemu * [new tag] patchew/20180621184116.910-1-alex.bennee@linaro.org -> patchew/20180621184116.910-1-alex.bennee@linaro.org Switched to a new branch 'test' 0a765327ad blogposts: add post about the new check-tcg infrastructure === OUTPUT BEGIN === Checking PATCH 1/1: blogposts: add post about the new check-tcg infrastructure... WARNING: added, moved or deleted file(s), does MAINTAINERS need updating? #13: new file mode 100644 ERROR: trailing whitespace #102: FILE: _posts/2018-06-21-tcg-testing.md:85: +need to be followed to add new tests? $ total: 1 errors, 1 warnings, 129 lines checked Your patch has style problems, please review. If any of these errors are false positives report them to the maintainer, see CHECKPATCH in MAINTAINERS. === OUTPUT END === Test command exited with code: 1 --- Email generated automatically by Patchew [http://patchew.org/]. Please send your feedback to patchew-devel@redhat.com
On 06/21/2018 06:12 PM, no-reply@patchew.org wrote: > This series seems to have some coding style problems. See output below for > more information: > > Type: series > Message-id: 20180621184116.910-1-alex.bennee@linaro.org > Subject: [Qemu-devel] [PATCH] blogposts: add post about the new check-tcg infrastructure [...]> === OUTPUT BEGIN === > Checking PATCH 1/1: blogposts: add post about the new check-tcg infrastructure... > WARNING: added, moved or deleted file(s), does MAINTAINERS need updating? > #13: > new file mode 100644 > > ERROR: trailing whitespace > #102: FILE: _posts/2018-06-21-tcg-testing.md:85: > +need to be followed to add new tests? $ =) > > total: 1 errors, 1 warnings, 129 lines checked > > Your patch has style problems, please review. If any of these errors > are false positives report them to the maintainer, see > CHECKPATCH in MAINTAINERS.
On Thu, Jun 21, 2018 at 11:41 AM, Alex Bennée <alex.bennee@linaro.org> wrote: > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > --- > _posts/2018-06-21-tcg-testing.md | 129 +++++++++++++++++++++++++++++++ > 1 file changed, 129 insertions(+) > create mode 100644 _posts/2018-06-21-tcg-testing.md > > diff --git a/_posts/2018-06-21-tcg-testing.md b/_posts/2018-06-21-tcg-testing.md [...] > +The `tests/tcg` directory still contains a number of source files we > +don't build. Notably the cris, lm32, mips, openrisc and xtensa targets have > +a set of tests that need a system emulator. Now we have the > +infrastructure for compiling I hope we can get support for system > +tests added fairly quickly. There will need to be some work to figure > +out a nice common way to pass results back to the build-system. For > +linux-user this is simple as all programs can simply return their exit > +code however for system emulation this is a little more involved. xtensa tests pass exit codes to the build system through semihosting calls. If any of them fails make check fails as well. -- Thanks. -- Max
Max Filippov <jcmvbkbc@gmail.com> writes: > On Thu, Jun 21, 2018 at 11:41 AM, Alex Bennée <alex.bennee@linaro.org> wrote: >> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> >> --- >> _posts/2018-06-21-tcg-testing.md | 129 +++++++++++++++++++++++++++++++ >> 1 file changed, 129 insertions(+) >> create mode 100644 _posts/2018-06-21-tcg-testing.md >> >> diff --git a/_posts/2018-06-21-tcg-testing.md b/_posts/2018-06-21-tcg-testing.md > > [...] > >> +The `tests/tcg` directory still contains a number of source files we >> +don't build. Notably the cris, lm32, mips, openrisc and xtensa targets have >> +a set of tests that need a system emulator. Now we have the >> +infrastructure for compiling I hope we can get support for system >> +tests added fairly quickly. There will need to be some work to figure >> +out a nice common way to pass results back to the build-system. For >> +linux-user this is simple as all programs can simply return their exit >> +code however for system emulation this is a little more involved. > > xtensa tests pass exit codes to the build system through semihosting calls. > If any of them fails make check fails as well. I've re-written that section as: The `tests/tcg` directory still contains a number of source files we don't build. The cris and openrisc directories contain user-space tests which just need the support of a toolchain and the relevant Makefile plumbing to be added. The lm32, mips and xtensa targets have a set of tests that need a system emulator. Aside from adding the compilers as docker images some additional work is needed to handle the differences between plain linux-user tests which can simply return an exit code to getting the results from a qemu-system emulation. Some architectures have semi-hosting support already for this while others report their test status over a simple serial link which will need to be parsed and handled in the `run-%:` test rule. How is that? Any chance you could look into what it would take to package up the xtensa toolchain in a docker container? Are they simply tarballs of binaries? -- Alex Bennée
On Fri, Jun 22, 2018 at 2:03 AM, Alex Bennée <alex.bennee@linaro.org> wrote: > > Max Filippov <jcmvbkbc@gmail.com> writes: > >> On Thu, Jun 21, 2018 at 11:41 AM, Alex Bennée <alex.bennee@linaro.org> wrote: >>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> >>> --- >>> _posts/2018-06-21-tcg-testing.md | 129 +++++++++++++++++++++++++++++++ >>> 1 file changed, 129 insertions(+) >>> create mode 100644 _posts/2018-06-21-tcg-testing.md >>> >>> diff --git a/_posts/2018-06-21-tcg-testing.md b/_posts/2018-06-21-tcg-testing.md >> >> [...] >> >>> +The `tests/tcg` directory still contains a number of source files we >>> +don't build. Notably the cris, lm32, mips, openrisc and xtensa targets have >>> +a set of tests that need a system emulator. Now we have the >>> +infrastructure for compiling I hope we can get support for system >>> +tests added fairly quickly. There will need to be some work to figure >>> +out a nice common way to pass results back to the build-system. For >>> +linux-user this is simple as all programs can simply return their exit >>> +code however for system emulation this is a little more involved. >> >> xtensa tests pass exit codes to the build system through semihosting calls. >> If any of them fails make check fails as well. > > I've re-written that section as: > > The `tests/tcg` directory still contains a number of source files we > don't build. > > The cris and openrisc directories contain user-space tests which just > need the support of a toolchain and the relevant Makefile plumbing to > be added. > > The lm32, mips and xtensa targets have a set of tests that need a > system emulator. Aside from adding the compilers as docker images some > additional work is needed to handle the differences between plain > linux-user tests which can simply return an exit code to getting the > results from a qemu-system emulation. Some architectures have > semi-hosting support already for this while others report their test > status over a simple serial link which will need to be parsed and > handled in the `run-%:` test rule. > > How is that? 'run-%' goal is only present in xtensa Makefile, other test suites have explicit loop in the 'check' goal. Otherwise LGTM. > Any chance you could look into what it would take to package up the > xtensa toolchain in a docker container? Can you point me to an example? > Are they simply tarballs of binaries? Yes, we have that option: https://github.com/foss-xtensa/toolchain/releases Or they may be built from source. -- Thanks. -- Max
Max Filippov <jcmvbkbc@gmail.com> writes: > On Fri, Jun 22, 2018 at 2:03 AM, Alex Bennée <alex.bennee@linaro.org> wrote: >> >> Max Filippov <jcmvbkbc@gmail.com> writes: >> >>> On Thu, Jun 21, 2018 at 11:41 AM, Alex Bennée <alex.bennee@linaro.org> wrote: >>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> >>>> --- >>>> _posts/2018-06-21-tcg-testing.md | 129 +++++++++++++++++++++++++++++++ >>>> 1 file changed, 129 insertions(+) >>>> create mode 100644 _posts/2018-06-21-tcg-testing.md >>>> >>>> diff --git a/_posts/2018-06-21-tcg-testing.md b/_posts/2018-06-21-tcg-testing.md >>> >>> [...] >>> >>>> +The `tests/tcg` directory still contains a number of source files we >>>> +don't build. Notably the cris, lm32, mips, openrisc and xtensa targets have >>>> +a set of tests that need a system emulator. Now we have the >>>> +infrastructure for compiling I hope we can get support for system >>>> +tests added fairly quickly. There will need to be some work to figure >>>> +out a nice common way to pass results back to the build-system. For >>>> +linux-user this is simple as all programs can simply return their exit >>>> +code however for system emulation this is a little more involved. >>> >>> xtensa tests pass exit codes to the build system through semihosting calls. >>> If any of them fails make check fails as well. >> >> I've re-written that section as: >> >> The `tests/tcg` directory still contains a number of source files we >> don't build. >> >> The cris and openrisc directories contain user-space tests which just >> need the support of a toolchain and the relevant Makefile plumbing to >> be added. >> >> The lm32, mips and xtensa targets have a set of tests that need a >> system emulator. Aside from adding the compilers as docker images some >> additional work is needed to handle the differences between plain >> linux-user tests which can simply return an exit code to getting the >> results from a qemu-system emulation. Some architectures have >> semi-hosting support already for this while others report their test >> status over a simple serial link which will need to be parsed and >> handled in the `run-%:` test rule. >> >> How is that? > > 'run-%' goal is only present in xtensa Makefile, other test suites have > explicit loop in the 'check' goal. Otherwise LGTM. The TCG tests added a generic run-% rule: run-%: % $(call run-test, $<, $(QEMU) $<, "$< on $(TARGET_NAME)") Although individual tests can override it. > >> Any chance you could look into what it would take to package up the >> xtensa toolchain in a docker container? > > Can you point me to an example? Well this was the base attempt: https://github.com/stsquad/qemu/commit/daee9dc013b13b13e81f720176c5e379c05ed0e0 So I guess we need to add the overlay to the image? > >> Are they simply tarballs of binaries? > > Yes, we have that option: > > https://github.com/foss-xtensa/toolchain/releases > > Or they may be built from source. -- Alex Bennée
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