If you're using dmidecode, then you need the uuid set. But, even with the hyphen format, usually dmidecode handles it -
uuid.location = "56 4d 1f bc b8 82 0a af-fe c4 2b a6 e7 04 0e a5"
dmidecode -t system
# dmidecode 2.11
SMBIOS 2.4 present.
Handle 0x0001, DMI type 1, 27 bytes
System Information
Manufacturer: VMware, Inc.
Product Name: VMware Virtual Platform
Version: None
Serial Number: VMware-56 4d 1f bc b8 82 0a af-fe c4 2b a6 e7 04 0e a5
UUID: 564D1FBC-B882-0AAF-FEC4-2BA6E7040EA5
Wake-up Type: Power Switch
SKU Number: Not Specified
Family: Not Specified
Notice the UUID matches the uuid.location. Have you tried dmidecode -s system-uuid? That number (with a little character manipulation) should get you results.
Reuben Stump | http://www.virtuin.com | @ReubenStump
