On Thursday 03 April 2008 09:54:51 am Rene Herman wrote: > However, now that you made me look closer and in context -- there's actually > a possibly somewhat serious problem here. > > isapnp_read_resources() stores the resources as read from the hardware at > the index in the table that matches the actual index in the hardware and > isapnp_set_resources() stores them back into those same hardware indices. > > Now by using pnp_add_foo_resource() which just scans for the first _UNSET > resource, the resources might not end up in the same linear position in > table/list if intermediate resources were unset in hardware (!ret). A > subsequent isapnp_set_resources() would them restore the value to the wrong > hardware index. > > The IORESOURCE_ flags currently reserve too few bits (IORESOURCE_BITS, 8) > to be able to store the hardware index: IORESOURCE_MEM and IORESOURCE_DMA > need 2 and 1 respectively and there are 1 and 0 available respectively. It's > ofcourse possible to hijack a few more bits in IORESOURCE_ flags but you're > turning this into a list. I suppose the idea is to make it a simple list of > struct resource, but perhaps a resource-private "driver_data" sort of field > comes in handy for more than this already? Swiping more of IORESOURCE_ is a > bit ugly... > > In any case, I missed this, but ISAPnP is still (at least in principle) > broken with the current set therefore. Hmm... you're right. And I think it could bite PNPBIOS and PNPACPI as well -- they don't read/write hardware registers directly, but the firmware still depends on preserving the resource order. I'll have to ponder that for a while. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
