question on CFLAGS

I'm getting this error when trying to compile freeswan:

cc  -DIPCOMP_PREFIX -include 
/root/freeswan-2.00/packaging/linus/config-all.h -I../../include 
-I/usr/src/linux/include  -I../../lib/zlib  -Wall -DARCH=sparc64 
 -DMODVERSIONS -include /usr/src/linux/include/linux/modversions.h 
-DMODULE -DMODVERSIONS -include 
/usr/src/linux-2.4.20-2.3sparc/include/linux/modversions.h 
 -D__KERNEL__ -I/usr/src/linux-2.4.20-2.3sparc/include -Wall 
-Wstrict-prototypes -Wno-trigraphs -O2 -fno-strict-aliasing 
-fno-common -fomit-frame-pointer -fomit-frame-pointer -m64 -pipe 
-mno-fpu -mcpu=ultrasparc -mcmodel=medlow -ffixed-g4 -fcall-used-g5 
-fcall-used-g7 -Wno-sign-compare -Wa,--undeclared-regs 
 -DKBUILD_BASENAME=ipsec_sha1  -c -o ipsec_sha1.o ipsec_sha1.c
Virtual memory exhausted!
make[1]: *** [ipsec_sha1.o] Error 1
make[1]: Leaving directory `/root/freeswan-2.00/linux/net/ipsec'
make: *** [module] Error 2

(Virtual memory exhausted) and according to some previous posts 
removing -O2 may do the trick in getting this to work.  I don't think 
mem/disk is at all an issue as I've got 512MB swap, and 2GB of memory 
and plenty of disk space free.  In any case.  I've run:

find . -name "Makefile*" -exec grep -H "O2" {} \;
and
find . -name "Makefile*.*" -exec grep -H "O2" {} \;
and
find . -name "Makefile*" -exec grep -H "CFLAGS" {} \;
and
find . -name "Makefile*.*" -exec grep -H "CFLAGS" {} \;

from the FreeSWAN build directory and from 
/usr/src/linux-2.4.20-2.3sparc

I'm looking for where I can delete or remove O2 from the CFLAGS to see 
if that fixes my build issue.  What other files might I search for to 
accomplish this task?

Thanks for any pointers,
--
"Try not.  Do or do not, there is no try." -Yoda