+cc linux-pci On Mon, Jun 20, 2011 at 10:38 AM, Armin Schindler <armin@xxxxxxxxxx> wrote: > On Mon, 20 Jun 2011, Armin Schindler wrote: >> >> Hello, >> >> when I try to map PCI resource of size < PAGE_SIZE to user space >> with e.g. remap_pfn_range() the mapping seems to be created, >> but the access to the PCI device just doesn't work (read returns 0xff). >> >> The same happens when using sysfs. The device has >> # ls -al /sys/bus/pci/devices/0000\:02\:09.0/resource* >> -rw------- 1 root root 512 Jun 20 11:33 >> /sys/bus/pci/devices/0000:02:09.0/resource0 >> -rw------- 1 root root 256 Jun 20 11:33 >> /sys/bus/pci/devices/0000:02:09.0/resource1 >> -rw------- 1 root root 8388608 Jun 20 11:33 >> /sys/bus/pci/devices/0000:02:09.0/resource2 >> -rw------- 1 root root 262144 Jun 20 11:33 >> /sys/bus/pci/devices/0000:02:09.0/resource3 >> >> and when I mmap() resource0, a valid address is returned, but reading the >> area always returns 0xff. >> >> Since a kernel driver can access resource0 here without problems when >> using >> ioremap(), I'm not sure what is wrong with the sysfs entry for user space >> (or using remap_pfn_range() in own mmap function). >> The only hint I have so far is the size, which is smaller than PAGE_SIZE. > > I found the reason. It is not the size of the resource. > The resource0 is assigned to a not page-aligned address. > Example, the pci resource0 has address 0xfe5ffc00. mmap()ing it will > actually seems to map address 0xfe5ff000 and the user needs to add 0xc00 to > the address returned by mmap(). > > Armin > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
