casaroli opened a new pull request, #3972:
URL: https://github.com/apache/nuttx-apps/pull/3972
## Summary
In a kernel build, `import/Make.defs` adds `-lm` only when
`CONFIG_LIBM_NONE` is set. The condition is inverted. Commit 877509762 ("Use
libm from the export package when defined") meant the opposite. This PR adds
`-lm` when a math library other than the one of the toolchain is selected.
## Impact
- Kernel builds only: the line is inside `ifeq ($(CONFIG_BUILD_KERNEL),y)`.
Flat and protected builds do not use it.
- `CONFIG_LIBM`: the export package has `libm.a`, but programs do not link
it. A program that calls a math function keeps undefined symbols. Its link
fails on rv-virt:knsh64. On qemu-armv8a:knsh the link gives no error, and
`exec()` fails: NSH prints "command not found".
- `CONFIG_LIBM_NONE`: the export package has no `libm.a`, so `make import`
fails with "cannot find -lm" for every program. This PR fixes this too.
- `CONFIG_LIBM_TOOLCHAIN`: no change.
- `tools/KernelLibs.mk` puts `libm.a` in the export package for every other
choice (`CONFIG_LIBM`, `CONFIG_LIBM_NEWLIB`, `CONFIG_LIBM_LIBMCS`,
`CONFIG_LIBM_OPENLIBM`).
- The import build is a make build only, so there is no CMake change. No
documentation change: Documentation/ does not describe this link.
## Testing
Test program `libmuse.c`: a program of the apps tree that `make import`
builds, and that calls `cbrt()` and `frexp()`. nuttx 39a1f27900c.
| configuration | master | this PR |
| --- | --- | --- |
| qemu-armv8a:knsh (`CONFIG_LIBM`, QEMU with HVF) | undefined `cbrt`,
`frexp`; "command not found" | no undefined symbols; PASS: `cbrt(27)` = 3,
`frexp(8)` = 0.5, exponent 4 |
| rv-virt:knsh64 (`CONFIG_LIBM`, QEMU TCG) | `make import` fails: undefined
reference to `cbrt`, `frexp` | no undefined symbols; PASS, same values |
| qemu-armv8a:knsh with `CONFIG_LIBM_NONE`, without the test program | `make
import` fails: "cannot find -lm" | `make import` OK, 6 programs (master: 0) |
ostest exits with status 0 on qemu-armv8a:knsh on master and with this PR.
No test in CI checks this: no citest configuration is a kernel build.
The tests ran on apps master 2a452d453; the branch is rebased on f04aee6015c
(no change in the touched files).
`tools/checkpatch.sh -c -u -m -g` passes.
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