When developing tests, it is much faster to use the QEMU Linux
emulator instead of the system emulator, which among other things avoids
kernel-build latencies. Although use of the QEMU Linux emulator does have
its limitations (please see below), it is sufficient to test startup code,
stdlib code, and syscall calling conventions.
However, the current mainline Linux-kernel nolibc setup does not
support this. Therefore, add a "run-user" target that immediately
executes the prebuilt executable.
Again, this approach does have its limitations. For example, the
executable runs with the user's privilege level, which can cause some
false-positive failures due to insufficient permissions. In addition,
if the underlying kernel is old enough to lack some features that
nolibc relies on, the result will be false-positive failures in the
corresponding tests. However, for nolibc changes not affected by these
limittions, the result is a much faster code-compile-test-debug cycle.
With this patch, running a userland test is as simple as issuing:
make ARCH=xxx CROSS_COMPILE=xxx run-user
Signed-off-by: Willy Tarreau <w@1wt.eu>
Tested-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Building the kernel with ARCH=x86_64 works fine, but nolibc-test
only supports "x86", which causes errors when reusing existing build
environment. Let's permit this environment to be used as well by making
nolibc also accept ARCH=x86_64.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Tested-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Paul and I got trapped a few times by not seeing the effects of applying
a patch to the nolibc source code until a "make clean" was issued in
the nolibc directory. It's particularly annoying when trying to confirm
that a proposed patch really solves a problem (or that reverting it
reintroduces the problem).
The reason for the sysroot not being rebuilt was that it can be quite
slow. But in fact it's only slow after a "make clean" issued at the
kernel's topdir, because it's the main "make headers" that can take a
tens of seconds; as long as "usr/include" still contains headers, the
"headers_install" phase is only a quick "rsync", and rebuilding the
whole nolibc sysroot takes a bit less than one second, which is perfectly
acceptable for a test, even more once the time lost caused by misleading
results is factored in.
This patch marks the sysroot target as phony and starts by clearing
the previous sysroot for the current architecture before reinstalling
it. Thanks to this, applying a patch to nolibc makes the effect
immediately visible to "make nolibc-test":
$ time make -j -C tools/testing/selftests/nolibc nolibc-test
make: Entering directory '/k/tools/testing/selftests/nolibc'
MKDIR sysroot/x86/include
make[1]: Entering directory '/k/tools/include/nolibc'
make[2]: Entering directory '/k'
make[2]: Leaving directory '/k'
make[2]: Entering directory '/k'
INSTALL /k/tools/testing/selftests/nolibc/sysroot/sysroot/include
make[2]: Leaving directory '/k'
make[1]: Leaving directory '/k/tools/include/nolibc'
CC nolibc-test
make: Leaving directory '/k/tools/testing/selftests/nolibc'
real 0m0.869s
user 0m0.716s
sys 0m0.149s
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Link: https://lore.kernel.org/all/20221021155645.GK5600@paulmck-ThinkPad-P17-Gen-1/
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
It presents the supported targets, and becomes the default target to
save the user from having to read the makefile. The "all" target was
placed after it and now points to "run" to do everything since it's
no longer the default one.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
It's not convenient to rely on a sysroot built in another directory,
especially when running cross-compilation tests, where one has to
switch back and forth between directories.
Let's make it possible to install the sysroot directly in the test
directory. It's not big and even benefits from being copied by arch
so that it's easier to switch between archs if needed. The new
"sysroot" target does this, it just calls "headers_standalone" from
nolibc to install the sysroot right here.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The "run" target will build the kernel and start it in QEMU. The
"rerun" target will not have the kernel dependency and will just try
to start QEMU. The QEMU architecture used to start the kernel is
derived from the configured ARCH. This might need to be improved
for archs which include different variants under the same name
(mips vs mipsel, +/-64, riscv32 vs riscv64). This could be tested
for i386, x86, arm, arm64, mips and riscv (the later two reporting
issues on some tests).
It is possible to pass a test specification for nolibc-test in the TEST
variable, which will be passed as-is as NOLIBC_TEST.
On success, the number of successful tests is printed. On failure, failed
lines are individually printed.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
While most archs will work fine with "make defconfig", not all will
do, and it's not always easy to remember the most suitable choice to
use for a specific architecture.
This adds a "defconfig" target to the Makefile so that one may easily
run "make -C ... defconfig" and make sure to clean and rebuild a fresh
config. This is *not* used by default because we want to preserve the
user's config by default.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The "kernel" target rebuilds the kernel with the current config for the
selected arch, with an initramfs containing the nolibc-test utility.
Since image names depend on the architecture, the currently supported
ones are referenced and resolved based on the architecture.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This creates a "nolibc" selftest that intends to test various parts of
the nolibc component, both in terms of build and execution for a given
architecture.
The aim is for it to be as simple to run as a kernel build, by just
passing the compiler (for the build) and the ARCH (for kernel and
execution).
It brings a basic squeleton made of a single C file that will ease testing
and error reporting. The code will be arranged so that it remains easy to
add basic tests for syscalls or library calls that may rely on a condition
to be executed, and whose result is compared to a value or to an error
with a specific errno value.
Tests will just use a relative line number in switch/case statements as
an index, saving the user from having to maintain arrays and complicated
functions which can often just be one-liners.
MAINTAINERS was updated.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
