Stelian Pop wrote: > Hi, > > I need to be able to map an IO memory buffer to userspace from a RTDM > driver. > > rtdm_mmap_to_user() seems to do what I need, but it doesn't work. Its > code thinks that all virtual addresses between VMALLOC_START and > VMALLOC_END are obtained through vmalloc() and tries to call > xnarch_remap_vm_page() on them, which fails.
Ok, interesting (one never stops learning). > > Virtual addresses coming from ioremap() need to go through > xnarch_remap_io_page_range(), and their physical address cannot be > obtained with a simple virt_to_phys(). > > A working patch is attached below, but there might (should ?) be a > better way to do it. Some of the code may also belong to > asm-generic/system.h instead of the RTDM skin. > > Note that you may also need to EXPORT_SYMBOL(vmlist and vmlist_lock) in > mm/vmalloc.c if you want to build the RTDM skin as a module. > > Comments ? In case no one comes up with an easy, portable way to detect remapped memory as well: What about some flags the caller of rtdm_mmap_to_user has to pass, telling what kind of memory it is? Would simplify the RTDM part, and the user normally knows quite well where the memory came from. And I love to break APIs. :) I'm CC'ing the first users of this service to ask for some feedback from their POV. Hope gna does not -once again- mangles the CCs. Jan
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