Task 4: Update Flash Memory With New JavaOS Image

Tower model computers may include flash memory to store the JavaOS image. After the JavaOS software finishes its initialization, it determines whether it needs to update the flash memory with a new JavaOS image based on the following criteria:

• The value of the JavaOS property javaos.alwaysUpdate

• Whether the JavaOS checksum value is different from the checksum of the JavaOS image already in flash

Both the property and the checksum are delivered by DHCP as Vendor-Specific Options. See "Vendor-Specific Options".

The JavaOS checksum identifies the revision level of the JavaOS image. For more information, see "Managing the JavaOS Checksum".

The results of each possible set of conditions are shown in the table below.

Table 2-2 Conditions for Updating JavaStation Flash Memory

Conditions		Results
javaos.alwaysUpdate	Checksum
Not set	different	JavaOS software opens a Flash Update dialog box on the JavaStation screen. The user has the option of updating flash memory with the new JavaOS binary.
Not set	same	JavaOS software does not update the flash memory.
true	different	JavaOS software updates flash memory without querying the user.
true	same	JavaOS software does not update the flash memory.
false	different	JavaOS software does not update the flash memory.
false	same	JavaOS software does not update the flash memory.

If the flash memory is updated, the JavaStation computer immediately reboots with the newly updated JavaOS image.

Note that if any of the following conditions exist, flash memory is never updated:

• javaos.alwaysUpdate is set to false

• The checksum is set to zero

• The checksum is not delivered by the DHCP server

• There is no flash memory on the JavaStation computer