Hi everyone. First, setting up context; kindly correct me if I am wrong :) In kernel-space : ----------------------- * We use ioremap to map a BAR-area physical-memory into kernel's virtual-address space. * We then need to use *special* accessor-functions (ioread/iowrite and friends) to ensure that the I/O is propagated through fine via path kernel-virtual-memory <=> BAR-physical-memory <=> device In user-space : ----------------------- * We mmap() a sysfs-file, which causes the kernel to map a userspace VMA to the same BAR-area physical-memory (using remap_pfn_range() or equivalent). * We then use *vanilla* dereferencing to read/write via path userspace-VMA <=> BAR-physical-memory <=> device. Now, my queries are regarding the usage of *special* accessor-functions in kernel-mode, versus *vanilla* dereferencing in user-mode. a) Firstly, is my assertion true? :) b) If yes, then how is the path userspace-VMA <=> BAR-physical-memory <=> device possible via *vanilla* dereferencing in user-mode? Will be grateful for insights .. Thanks and Regards, Ajay
