Well, like many kernel options, it does depend on other things. For
example, if swap (General Setup / support for paging anonymous memory
(swap)) isn't enabled, you won't get an option for software suspend.
>From 'kernel/power/Kconfig':
config SOFTWARE_SUSPEND
bool "Software Suspend"
depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP) && !X86_PAE) ||
((FRV || PPC32) && !SMP))
---help---
Enable the possibility of suspending the machine.
It doesn't need ACPI or APM.
You may suspend your machine by 'swsusp' or 'shutdown -z <time>'
(patch for sysvinit needed).
Celejar