cheribuild - Adding a new target

Hi,

In your code `no` is a python variable, which isn't defined. What you want to be using is either self.add_cmake_options(WITH_DOCS=False) if the project expects a CMake boolean (i.e. ON/OFF/TRUE/FALSE) or self.add_cmake_options(WITH_DOCS="no") if the project does a string comparison.

Hi there,

Thanks for your response. The project is expecting a string comparison so I've added self.add_cmake_options(WITH_DOCS="no"). 

The build is still erroring out because it can't find xsltproc to generate the man pages, even though I've told it to skip that step:

CMake Error at man/CMakeLists.txt:29 (message):
    xsltproc not found: manpages cannot be built
-- Configuring incomplete, errors occurred!

Any ideas on how best to resolve this?

I don't see WITH_DOCS mentioned anywhere in the CMakeLists.txt there. However, there is a 

so you should be able to use self.add_cmake_options(DOCUMENTATION=False).

I'd recommend opening an issue with the project and tell them that their documentation is out-of-date.

It's always been that https://github.com/eclipse/mosquitto/commit/3163cf2d709e7b021867aec2e811331991ad097a. Someone just put the wrong thing in the README, presumably wasn't thinking and assumed it followed the same pattern as all the other options which do use WITH_FOO.

Ah. It's WITH_DOCS for the Makefile, and the README talks about make. For CMake it just says "Equivalent options for enabling/disabling features are available when using the CMake build".

Filed as github.com/.../2272

Thanks for the clarification Jessica :) It seems to build perfectly now

Another quick question on this. Do I have to use an upstream Git repository as I have with this Python script, or can I use another method such as referencing a local directory if I have already downloaded the source manually? Or maybe another method? Thanks

I have ran into another error when trying to cross-compile tcpdump. I have tried create a Python script to add it as a cheribuild target, and also cross-compiling manually with:

CC="$HOME/cheri/output/morello-sdk/bin/clang --target=aarch64-unknown-freebsd13 --sysroot=$HOME/cheri/output/rootfs-morello-purecap" CFLAGS="-march=morello+c64 -mabi=purecap -femulated-tls" LDFLAGS="-fuse-ld=lld" PKG_CONFIG_PATH= PKG_CONFIG_LIBDIR= ./configure --host=aarch64-unknown-freebsd13

...but I keep getting the same error and the build stops:

checking whether printf(3) supports the z length modifier... configure: error: in `/home/ubuntu/tcpdump':
configure: error: cannot run test program while cross compiling
See `config.log' for more details

The "tests" folder in the source directory is the last thing accessed by the configure script but keeps erroring out. Looking at the config.log, this is what is displayed with relation to that error:

conftest.c:66:6: note: 'snprintf' is a builtin with type 'int (char *, unsigned long, const char *, ...)'1 warning generated.
configure:4963: $? = 0
configure:4963: result: yes
configure:4975: checking whether printf(3) supports the z length modifier
configure:4978: error: in `/home/ubuntu/tcpdump':
configure:4980: error: cannot run test program while cross compiling
See `config.log' for more details

samDobson said:

Another quick question on this. Do I have to use an upstream Git repository as I have with this Python script, or can I use another method such as referencing a local directory if I have already downloaded the source manually? Or maybe another method? Thanks

If you have a local directory with sources you can use 

repository = ExternallyManagedSourceRepository()

to skip the update step for cheribuild. You will have to ensure the sources are in the expected directory or manually set the "<project>/source-directory" config option.

samDobson said:

checking whether printf(3) supports the z length modifier... configure: error: in `/home/ubuntu/tcpdump':
configure: error: cannot run test program while cross compiling
See `config.log' for more details

Autotools is a terrible "build system" so often requires various workarounds when cross-compiling. The same issue happened with PostgreSQL and there the workaround is:

            # tell postgres configure that %zu works in printf()
            self.add_configure_and_make_env_arg("PRINTF_SIZE_T_SUPPORT", "yes")

However, since autotools build scripts are essentially just shell scripts that use arbitrary variable naming conventions, tcpdump may well be using a different environment variable for this. You'll have to look at the generated configure script to find out which variable they decided to use.

Alex Richardson said:

to skip the update step for cheribuild. You will have to ensure the sources are in the expected directory or manually set the "<project>/source-directory" config option.

I'm not sure what you mean by this above.

Also, what is the CheriConfig module imported in the postgres.py script and what is the purpose of this?

And looking at the configure script, the portion of the script that is erroring out is this:

#
# Define HAVE_NO_PRINTF_Z to make it possible to disable test cases that
# depend on %zu.
#
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether printf(3) supports the z length modifier" >&5
$as_echo_n "checking whether printf(3) supports the z length modifier... " >&6; }
if test "$cross_compiling" = yes; then :
{ { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
as_fn_error $? "cannot run test program while cross compiling
See \`config.log' for more details" "$LINENO" 5; }
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */

However, I'm not sure which environment variable I have to manipulate to bypass these checks. I am guessing it is HAVE_NO_PRINTF_Z but I am not sure if that is even an environment variable, or how to define that in the Python build script. In the configure.ac file, the following is defined:

AC_DEFINE(HAVE_NO_PRINTF_Z, 1,
[Define to 1 if printf(3) does not support the z length modifier.])

So my question is how do I manipulate the configure.ac file through the Python build scripts for my project?

After researching further into this, it seems to not be a problem at all with printf() supporting the z length modifier, but instead, the configure script is erroring out because it is trying to run tests, which it cannot do because the target binary is being cross-compiled and doesn't understand it. Output from the configure script:

if test "$cross_compiling" = yes; then :
{ { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
as_fn_error $? "cannot run test program while cross compiling
See \`config.log' for more details" "$LINENO" 5; }
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */

Is there a way I can amend the Python build script to include a Site Default which includes: cross_compiling=no to skip this test?

cross_compiling is being set to yes at this portion of the configure script when checking if the build machine is the same as the target machine:

elif test "x$build_alias" != "x$host_alias"; then
cross_compiling=yes

So I managed to disable this from happening manually by editing out....

as_fn_error

from the configure script to stop it erroring and cancelling the build. It now builds just fine. I am still unsure how this would equate to amendments to a Python build script.

That is far from a fix, and may be causing subtle mis-compiles. The correct thing to do is to find out what the test is doing, find out what variable it's using for the test result and manually specify the value for the variable so the test is skipped, normally via something like self.add_configure_vars(ac_cv_foo="bar") in your target's setup function.