Messages in this thread | | | Date | Tue, 28 Apr 2015 17:32:27 -0400 | From | Rob Harris <> | Subject | custom block device driver with 6k block size... |
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Greetings.
I've been working on developing a custom block device that (unfortunately) uses 6k block sizes. I've been trying to deal directly with the BIO's (make_request_fn) and even though I've configured the request_queue as follows...
blk_queue_io_min( smc_dev->req_queue, SIX_KB ); blk_queue_io_opt( smc_dev->req_queue, TWELVE_KB ); blk_queue_max_segments( smc_dev->req_queue, SIX_KB * 100 / TWELVE_KB ); blk_queue_max_segment_size( smc_dev->req_queue, SIX_KB * 100 ); blk_queue_max_hw_sectors( smc_dev->req_queue, SIX_KB * 100 / 512 ); blk_queue_logical_block_size( smc_dev->req_queue, SIX_KB ); blk_queue_physical_block_size( smc_dev->req_queue, SIX_KB ); blk_queue_segment_boundary( smc_dev->req_queue, SIX_KB-1 );
queue_flag_set_unlocked( QUEUE_FLAG_NONROT, smc_dev->req_queue ); queue_flag_clear_unlocked( QUEUE_FLAG_ADD_RANDOM, smc_dev->req_queue );
... I still seem to always get handed BIO's with PAGE_SIZE(4k) segment_sizes in the bio_vec and I never seem to get any sort of bio_vec coalescing when trying a blk_bio_map_sg. Everything returned is always small (if at all) multiples of PAGE_SIZE. I would love to DMA large buffers directly back and forth to the controller, but offsetting the delta between the 4k and 6k offset is a pain.
Is there something simple that I'm missing or doing wrong?
Thanks, -Rob Harris
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