blk_queue_bounce_limit (9) - Linux Manuals
blk_queue_bounce_limit: set bounce buffer limit for queue
blk_queue_bounce_limit - set bounce buffer limit for queue
void blk_queue_bounce_limit(struct request_queue
* q, u64 max_addr);
- the request queue for the device
- the maximum address the device can handle
Different hardware can have different requirements as to what pages it can do I/O directly to. A low level driver can call blk_queue_bounce_limit to have lower memory pages allocated as bounce buffers for doing I/O to pages residing above max_addr.