bwa index problem about bwa HOT 1 OPEN

hello, I got the same error with a large fasta file (ref.fa, of which single sequences is over 2 G)

bwa index -a bwtsw ref.fa
[bwa_index] Pack FASTA... 5.40 sec
[bwa_index] Construct BWT for the packed sequence...
Floating point exception (core dumped)

I tried simpliy bwa index ref.fa, it generated no error, but index results nearly contain nothing
[bwa_index] Pack FASTA... 5.57 sec
[bwa_index] Construct BWT for the packed sequence...
[bwa_index] 0.00 seconds elapse.
[bwa_index] Update BWT... 0.00 sec
[bwa_index] Pack forward-only FASTA... 5.37 sec
[bwa_index] Construct SA from BWT and Occ... 0.00 sec
[main] Version: 0.7.17-r1188
[main] CMD: bwa index ref.fa
[main] Real time: 10.974 sec; CPU: 10.942 sec

du -sh ref*
4.0K ref.fa.amb
4.0K ref.fa.ann
4.0K ref.fa.bwt
4.0K ref.fa.pac
4.0K ref.fa.sa

cat ref.fa.ann
0 0 11

from bwa.