On Thu, Oct 08, 2015 at 03:49:54PM +0100, Andre Przywara wrote: > Hi, > > On 08/10/15 11:38, Alexandre Belloni wrote: > > On 08/10/2015 at 10:37:49 +0100, Russell King - ARM Linux wrote : > >> On Thu, Oct 08, 2015 at 11:01:48AM +0200, Alexandre Belloni wrote: > >>> On 05/10/2015 at 18:00:52 +0100, Andre Przywara wrote : > >>>> Turning on KVM and LPAE support on top of a multi_v7_defconfig will > >>>> produce a compiler warning in the Atmel serial driver: > >>>> drivers/tty/serial/atmel_serial.c: In function 'atmel_verify_port': > >>>> drivers/tty/serial/atmel_serial.c:2299:6: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] > >>>> if ((void *)port->mapbase != ser->iomem_base) > >>>> ^ > >>>> > >>>> Fix that by using the cast on the right hand side instead, as similar > >>>> code already does in other drivers. > >>>> > >>>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx> > >>> Acked-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> > >> > >> Hmm, this actually points at a problem, and the cast screems out about it. > >> Think about it, can you guess what it is? > > Russell, I'd really appreciate if we wouldn't have to play > "guess-what-I-am-thinking" here. Can't you just say what's bothering you? Actually, I think it's fine - the interface is just another one of the weird cases we have in the kernel. However, for the record, things get typed a certain way for a reason. Virtual addresses that can be dereferenced are generally pointer like. Physical addresses are generally integers. Casting between the two generally indicates a bug, and whenever you see a cast between the two, it should have special attention paid to it to make sure that it really is correct. There are a few famous places in the kernel where casting between an unsigned long and a virtual address is pretty standard, but they're the exception to the rule (eg, the argument to a timer, get_free_page()). This is another example. Sorry for creating confusion. -- FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
