[PATCH v2 0/3] tools/nolibc: Support vprintf() so we can use kselftest.h with nolibc

[Mark Brown]

At present the kselftest header can't be used with nolibc since it makes
use of vprintf() which is not available in nolibc.  Fortunately nolibc
has a vfprintf() so we can just wrap that in order to allow kselftests
to be built with nolibc and still use the standard kselftest headers
with a small change to prevent the inclusion of the standard libc
headers.  This allows us to avoid open coding of KTAP output for
selftests that need to use nolibc in order to test interfaces that are
controlled by libc, we've got several open coded examples of this in the
tree already.

As an example of using this the existing za-fork test is converted to
use kselftest.h.  The changes to kselftest and nolibc don't have any
interaction until they are used by a test so could be merged separately
if desired.

Signed-off-by: Mark Brown <broonie at kernel.org>
---
Changes in v2:
- Turns out nolibc has a vfprintf() already which we can use so do that.
- Link to v1: https://lore.kernel.org/r/20230405-kselftest-nolibc-v1-0-63fbcd70b202@kernel.org

---
Mark Brown (3):
      tools/nolibc/stdio: Implement vprintf()
      kselftest: Support nolibc
      kselftest/arm64: Convert za-fork to use kselftest.h

 tools/include/nolibc/stdio.h               |  6 ++
 tools/testing/selftests/arm64/fp/Makefile  |  2 +-
 tools/testing/selftests/arm64/fp/za-fork.c | 88 ++++++------------------------
 tools/testing/selftests/kselftest.h        |  2 +
 4 files changed, 25 insertions(+), 73 deletions(-)
---
base-commit: e8d018dd0257f744ca50a729e3d042cf2ec9da65
change-id: 20230405-kselftest-nolibc-cb2ce0446d09

Best regards,
-- 
Mark Brown <broonie at kernel.org>