Building OpenBLAS with `TARGET=GENERIC` on ppc64le fails

[benrichard-amd]

Summary

Building OpenBLAS with TARGET=GENERIC on ppc64le fails at CMake configure time because kernel/power/KERNEL.generic does not exist.

Building with TARGET=POWER or TARGET=POWER9 is successful.

Steps to reproduce

On a ppc64le machine:

git clone https://github.com/OpenMathLib/OpenBLAS
cd OpenBLAS
cmake -B build -DTARGET=GENERIC

Error

-- Reading vars from /home/user/OpenBLAS/kernel/power/KERNEL...
-- Reading vars from /home/user/OpenBLAS/kernel/power/KERNEL.generic...
CMake Error at cmake/utils.cmake:59 (file):
  file STRINGS file
  "/home/user/OpenBLAS/kernel/power/KERNEL.generic"
  cannot be read.
Call Stack (most recent call first):
  kernel/CMakeLists.txt:40 (ParseMakefileVars)
  kernel/CMakeLists.txt:1556 (build_core)

-- Configuring incomplete, errors occurred!

Environment

• Architecture: ppc64le (POWER9)
• OS: RHEL 8 / Linux
• OpenBLAS version: latest develop

[martin-frbg]

Is there a need for a dedicated plain-C target on POWER ? "TARGET=GENERIC" does work in the context of DYNAMIC_ARCH builds (where it ensures that no fancy compiler options will be used for the common code). As a dedicated target, nobody appears to have missed it in all these years

[martin-frbg]

(And TARGET=POWER seems to be a fluke of the CMake build, it appears to ignore that argument and autodetects the build host. The gmake build would exit immediately with a message to use one of the targets from TargetList.txt)