DCC and interrupts

The use of DCC interrupts has significant speed implications when using Virtual Ethernet/TTY mode. If possible, you must tie DCC interrupts into the interrupt system of the target and be able to enable and disable the read and write interrupt individually.

Note

This is a configuration item that you must select when configuring the kernel, when using an ARM driver.

debug hardware uses JTAG to control debug operations, and JTAG is used to send and receive data over DCC. debug hardware polls the target JTAG for status:

If debug hardware finds that there is data to be transferred into or out of DCC, it attempts to transfer as many words as possible in one burst, up to a predefined limit. However, if the target has not sent more data or emptied its transfer register, debug hardware breaks out of its burst and begins polling the execution status and DCC.

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