st20-gp6 STMicroelectronics, st20-gp6 Datasheet - Page 29

• Manufacturer Part Number: st20-gp6
• Description: Gps Processor
• Manufacturer: STMicroelectronics

4.6.5
There are various restrictions that must be placed on trap handlers to ensure that they work cor-
rectly.
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Restrictions on trap handlers
Trap handlers must not deschedule or timeslice. Trap handlers alter the Enables masks,
therefore they must not allow other processes to execute until they have completed.
Trap handlers must have their Enable masks set to mask all traps in their trap group to
avoid the possibility of a trap handler trapping to itself.
Trap handlers must terminate via the tret (trap return) instruction . The only exception to this
is that a scheduler kernel may use restart to return to a previously shadowed process.
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