METHOD OF OPERATING A COMPUTING DEVICE THROUGH THE USE OF EXTENSIBLE THREAD STATES
A personality layer running above an operating system kernel puts any threads that the personality layer is responsible for into new states which the kernel does not know about. This prevents the kernel from performing operations on a thread which has been placed in one of these new states where these operations are sensitive to state of the thread itself (such as kill, suspend, change priority). Instead, the kernel redirects these thread operations to a handler in the personality layer which then handles the operation. The kernel is thus, in essence, extensible through the use of the added personality layers, and it can therefore be used to run legacy real-time applications written for other real-time operating systems.
1 . A method of implementing a personality layer for a first operating system on a computing device running a second operating system which enables software written for the said first operating system to run on the device by means of
a. the addition of extra states to the threads of execution running on the computing device by the personality layer; and
b. the kernel of the second operating system dispatching threads which are in these extra states to a handler in the personality layer.
2 . A computing device arranged to operate in accordance with a method as claimed in claim 1 .
3 . An operating system for causing a computing device to operate in accordance with a method as claimed in claim 1 .