[PATCH 1/4] docs: Add documentation about tests and SBIUnit

[Andrew Jones <ajones@ventanamicro.com>]

On Tue, Feb 13, 2024 at 02:54:17PM +0000, Ivan Orlov wrote:
> On 2/13/24 13:51, Andrew Jones wrote:
> > On Mon, Feb 12, 2024 at 09:48:02PM +0000, Ivan Orlov wrote:
> > > On 2/12/24 17:20, Andrew Jones wrote:
> > ...
> > > > But I think we should be able to add the test suite pointer to an elf
> > > > section with the SBIUNIT_TEST_SUITE() macro to avoid this step.
> > > > 
> > > 
> > > That was an initial idea, however I faced some obstacles during the
> > > implementation.
> > > 
> > > I believe we would like to cover the static functions, as well as use static
> > > variables in the tests. In this case, we would include the test in the
> > > source we are covering (for instance, include "sbi_console_test.c" in
> > > "sbi_console.c"). If we use OpenSBI (libplatsbi.a) as a library when linking
> > > firmware, and firmware refers to a symbol from "sbi_console.h", it will
> > > automatically link the test code too. This means that firmware should have
> > > the test ELF section as well. Manual registration of the tests in
> > > 'sbi_unit.c', on the other hand, would not require any effort from the
> > > firmware developers if they decide to enable tests for OpenSBI.
> > 
> > Hmm, I see. So maybe we can use the build system's carray?
> > 
> 
> Hmmm, I've never heard about this thing before, could you please point me to
> a reference or source where I could read about it?

It's used in OpenSBI code for arrays such as sbi_ecall_exts. See commit
56bed1a0fe39 ("lib: sbi_ecall: Generate extensions list with carray") for
that example.

> 
> > > 
> > > Moreover, manual test declaration will make sure that we included all of the
> > > tests. Otherwise, if we define the test in a separate file, it will be
> > > linked out unless we refer to symbols from it somewhere.
> > 
> > This could possibly be worked around with the linker's --whole-archive
> > option.
> 
> In this case we would have to update the makefile logic, because now OpenSBI
> uses 'compile_elf' makefile procedure for the test payload and the firmware
> elf files both, and we would not like to use --whole-archive for the test
> payload. I guess it is an overcomplication...

Maybe, but I'm not sure how much we'd care about having bloated binaries
when building with CONFIG_SBIUNIT.

Thanks,
drew