Re: fcp handling
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From: Manfred W. <e95...@st...> - 2000-04-05 16:48:20
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Andreas Bombe wrote: > [concerning the buffers which are handed over to the iso- or fcp-handlers] > The buffer is only overwritten on a raw1394_loop_iterate() call which > then calls the handlers. After a handler ends, the corresponding data > is invalid (the handler must process the data immediately or save it > somewhere else if it really has to store plain data). Therefore there > won't be problems with correct usage. Is the data really invalid, when the handler ends, or does it stay valid until the next call of raw1394_loop_iterate()? Imagine an application which processes data that arrives on an isochannel; and everytime, when its buffer is empty, it does (one or more) raw1394_loop_iterate() until the iso_handler is executed. Does the handler really have to copy the data to a separate buffer, or would it be sufficient to store the address of the (internal) buffer in a (global) variable? The premise is - of course - that raw1394_loop_iterates (on that particular raw-handle) is only done, when we need a new iso-packet. > In the future the address given to an iso or FCP handler might not > even exist anymore since I intend to implement kernel-to-user memory > mapping at some point in the future and the page containing the data > could be unmapped immediately after use. I think, that has no effet to my question above, isn't it? Manfred Weihs |