> ERROR: "sys_open" [kernel/cpt/vzrst.ko] undefined!
> ERROR: "sys_open" [kernel/cpt/vzcpt.ko] undefined!
> make[1]: *** [__modpost] Error 1
> make: *** [modules] Error 2
> + exit 1

this seems to have been fixed recently, and now checkpointing
compiles on amd64 (doesn't seem to work yet though:)

venom:/home/eyck# vzctl chkpnt 32
Setting up checkpoint...
	suspend...
	dump...
Can not dump VE: Invalid argument
Error: unknown restart block ffffffff802b0f9a
Checkpointing failed
and:
CPT ERR: ffff81006ed18000,101 :unknown restart block ffffffff802b0f9a
CPT ERR: ffff81006ed19800,32 :unknown restart block ffffffff802b0f9a
CPT ERR: ffff810070d20800,64 :unknown restart block ffffffff802b0f9a

-- 
Key fingerprint = 40D0 9FFB 9939 7320 8294  05E0 BCC7 02C4 75CC 50D9
 Total Existance Failure