IODMACommand->genIOVMSegments
IODMACommand->genIOVMSegments
- Subject: IODMACommand->genIOVMSegments
- From: devmaillists <email@hidden>
- Date: Tue, 19 Dec 2006 19:09:17 +0100
Hello List,
I need some additional information to genIO64VMSegments. Google does not really find something about this. We are writing a driver for a PCI Card and DMA Data should be transferred in multiples of 4K ( page size ). This is because of the memory layout on the card and to let the card take a breath between the transfers.
If if I set initWithSpecification maxSegmentSize to 4K ( I expect this to be the native page size), do I get only 4K "physically continous segments" with IOVMSegments. Sure the last one will be short.
Is there a way to tell the IOMemoryDescriptor to generate physically continous segments with a defined size?.
Is there a general rule how large a MemDesc can be to get prepared without igniting a lot of paging?
Thank you very much for help.
Best regards Mit freundlichen Grüßen Jürgen Sauerzapf
Ingenieurbüro Sauerzapf Friedrich Ebert Str. 32 55257 Budenheim tel: 06139 2256
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