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Trouble compiling GotoBLAS2 on newer CPU

13 May 2011

I came across a problem compiling GotoBLAS2 at work today. It went well on a practice cluster, but on the new one I got this error:

gcc -c -O2 -Wall -m64 -DF_INTERFACE_G77 -fPIC  -DSMP_SERVER -DMAX_CPU_NUMBER=24 -DASMNAME=strmm_ounncopy -DASMFNAME=strmm_ounncopy_ -DNAME=strmm_ounncopy_ -DCNAME=strmm_ounncopy -DCHAR_NAME=\"strmm_ounncopy_\o
../kernel/x86_64/gemm_ncopy_4.S: Assembler messages:
../kernel/x86_64/gemm_ncopy_4.S:192: Error: undefined symbol `RPREFETCHSIZE' in operation
../kernel/x86_64/gemm_ncopy_4.S:193: Error: undefined symbol `RPREFETCHSIZE' in operation
../kernel/x86_64/gemm_ncopy_4.S:194: Error: undefined symbol `RPREFETCHSIZE' in operation
../kernel/x86_64/gemm_ncopy_4.S:195: Error: undefined symbol `RPREFETCHSIZE' in operation
../kernel/x86_64/gemm_ncopy_4.S:197: Error: undefined symbol `WPREFETCHSIZE' in operation
../kernel/x86_64/gemm_ncopy_4.S:345: Error: undefined symbol `RPREFETCHSIZE' in operation
../kernel/x86_64/gemm_ncopy_4.S:346: Error: undefined symbol `RPREFETCHSIZE' in operation
../kernel/x86_64/gemm_ncopy_4.S:348: Error: undefined symbol `WPREFETCHSIZE' in operation

The solution was simple:

gmake clean
gmake TARGET=NEHALEM

The problem appears to be that newer CPUs (Intel X5650 in my case) are not detected properly by the CPU ID routine in GotoBlas2. You can verify this by checking the contents of config.h in the top-level directory. Without TARGET=NEHALEM, I saw this line:

#define INTEL_UNKNOWN

But with TARGET=NEHALEM, this becomes:

#define NEHALEM

The problem with gemm_ncopy_4.S arises because it defines RPRETCHSIZE and WPREFETCHSIZE using #ifdef statements depending on CPU type. There is an entry for #ifdef GENERIC, but that was not set for me in config.h.

In addition, if you type "gmake TARGET=NEHALEM" without "gmake clean" first, you get a little further before you run into a similar error:

usr/bin/ld: ../libgoto2_nehalemp-r1.13.a(ssymv_U.o): relocation R_X86_64_32S against `PREFETCHSIZE' can not be used when making a shared object; recompile with -fPIC
../libgoto2_nehalemp-r1.13.a(ssymv_U.o): could not read symbols: Bad value

If I was a better person, I'd have a look at how the sizes are defined and figure out what the right value is for newer CPUs, then modify cpuid.c (which I presume is what's being used to generate config.h, or at least this part of it. Maybe another day...

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