Build fails on Ubuntu 20.04 aarch64 with undefined reference to 'WhereAmI'

[SurvivorNo1]

Environment

- version: OpenBLAS-0.3.7
- OS: Ubuntu 20.04.2 LTS (Focal Fossa)
- CPU details:
Architecture: aarch64
CPU op-mode(s): 64-bit
Byte Order: Little Endian
CPU(s): 64
On-line CPU(s) list: 0-63
Thread(s) per core: 1
Core(s) per socket: 64
Socket(s): 1
NUMA node(s): 8
Vendor ID: 0x70
Model: 2
Stepping: 0x1
BogoMIPS: 100.00
L1d cache: 2 MiB
L1i cache: 2 MiB
L2 cache: 256 MiB
NUMA node0 CPU(s): 0-7
NUMA node1 CPU(s): 8-15
NUMA node2 CPU(s): 16-23
NUMA node3 CPU(s): 24-31
NUMA node4 CPU(s): 32-39
NUMA node5 CPU(s): 40-47
NUMA node6 CPU(s): 48-55
NUMA node7 CPU(s): 56-63
Vulnerability Itlb multihit: Not affected
Vulnerability L1tf: Not affected
Vulnerability Mds: Not affected
Vulnerability Meltdown: Mitigation; PTI
Vulnerability Spec store bypass: Vulnerable
Vulnerability Spectre v1: Mitigation; __user pointer sanitization
Vulnerability Spectre v2: Vulnerable
Vulnerability Srbds: Not affected
Vulnerability Tsx async abort: Not affected
Flags: fp asimd evtstrm crc32 cpuid

Issue description

Encountered a build error when compiling OpenBLAS on aarch64 architecture. The specific error message is

/usr/bin/ld: ../libopenblas_armv8p-r0.3.7.a(init.o): in function `gotoblas_set_affinity':
init.c:(.text+0xf8): undefined reference to `WhereAmI'
/usr/bin/ld: ../libopenblas_armv8p-r0.3.7.a(init.o): in function `get_node':
init.c:(.text+0x14c): undefined reference to `WhereAmI'
collect2: error: ld returned 1 exit status
make[1]: *** [Makefile:146: zblat1] Error 1
make[1]: *** Waiting for unfinished jobs....
/usr/bin/ld: ../libopenblas_armv8p-r0.3.7.a(init.o): in function `gotoblas_set_affinity':
init.c:(.text+0xf8): undefined reference to `WhereAmI'
/usr/bin/ld: ../libopenblas_armv8p-r0.3.7.a(init.o): in function `get_node':
init.c:(.text+0x14c): undefined reference to `WhereAmI'
collect2: error: ld returned 1 exit status
make[1]: *** [Makefile:143: cblat1] Error 1

Steps to Reproduce

1. Set the following configuration in Makefile.rule:

   NUM_THREADS = 64
   USE_OPENMP = 1
   NO_AFFINITY = 0
   

2. Run the following build command:

   nohup make NO_AFFINITY=0 -j32 &> makelog &
   

Error Message

The build fails with the following output:

undefined reference to 'WhereAmI'

Log Files and output

see the attachment

[martin-frbg]

do you really need to build a version from almost five years ago ?

[brada4]

set affinity with omp is absolutely unnecessary. Omp does manage affinity by itself. You need newer openblas, release from here or at least build dsc/dpkg from later/st ubuntu code.
I remember time I cleaned whereami, likely some aarch64 branch caried it back in rarely used patameter combo. Id assume it is long cleaned up.

[SurvivorNo1]

Thank you both for your input! I understand your points, but I need to maintain consistency with the environment described in a particular research paper. Therefore, I do need to build a version from almost five years ago. However, I will also try the latest version as suggested. I appreciate your and will close this issue.

[brada4]

You need slow netlib lapack for consistency, openblas like any other accelerated library will diverge few bits precision from reference.

[martin-frbg]

Hmm, this is interesting. I suspect this problem persists in the current codebase, but is only triggered by NO_AFFINITY=0

[brada4]

IMO something following this?
2601cd5

[martin-frbg]

@brada4 no, not directly related to that. Setting up for handling affinity requires fetching the numerical ID of the cores each thread is running on, which is what WhereAmI is supposed to deliver. Unfortunately I'm not quite clear on how to parse the MPIDR_EL1 output on aarch64, a quick kludge would be to put the following function in common_arm64.h
somewhere below the #ifndef ASSEMBLER line

static inline int WhereAmI(void){
 uint64_t ret;
  __asm__ volatile (
        "         mrs x0, mpidr_el1     \n"
        "         and x0, x0, 0xff \n"
                  :"=r" (ret)
                  :: "memory"
                );
  if (ret >MAX_CPU_NUMBER) ret=MAX_CPU_NUMBER;
  return (int)ret;
}

or just make it

static inline int WhereAmI(void){
return (sched_getcpu());
}

if you are on Linux with a fairly recent glibc

[brada4]

Or noop it...

[martin-frbg]

Or noop it...

strange suggestion when compiling with NO_AFFINITY=0 on purpose.