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SubjectRe: drivers/pci/probe.c compile warnings on -tip
Steven Noonan writes:
> I was hunting down some warnings I got when compiling -tip, and with
> one of them, I'm not sure what would be a proper way to handle it.
>
> If CONFIG_PHYS_ADDR_T_64BIT is not enabled, these warnings show up:
>
> drivers/pci/probe.c: In function '__pci_read_base':
> drivers/pci/probe.c:308: warning: format '%llx' expects type 'long
> long unsigned int', but argument 4 has type 'resource_size_t'
> drivers/pci/probe.c:308: warning: format '%llx' expects type 'long
> long unsigned int', but argument 5 has type 'resource_size_t'
> drivers/pci/probe.c:320: warning: format '%llx' expects type 'long
> long unsigned int', but argument 5 has type 'resource_size_t'
> drivers/pci/probe.c:320: warning: format '%llx' expects type 'long
> long unsigned int', but argument 6 has type 'resource_size_t'
> drivers/pci/probe.c: In function 'pci_read_bridge_bases':
> drivers/pci/probe.c:392: warning: format '%llx' expects type 'long
> long unsigned int', but argument 3 has type 'resource_size_t'
> drivers/pci/probe.c:392: warning: format '%llx' expects type 'long
> long unsigned int', but argument 4 has type 'resource_size_t'
> drivers/pci/probe.c:405: warning: format '%llx' expects type 'long
> long unsigned int', but argument 3 has type 'resource_size_t'
> drivers/pci/probe.c:405: warning: format '%llx' expects type 'long
> long unsigned int', but argument 4 has type 'resource_size_t'
> drivers/pci/probe.c:443: warning: format '%llx' expects type 'long
> long unsigned int', but argument 4 has type 'resource_size_t'
> drivers/pci/probe.c:443: warning: format '%llx' expects type 'long
> long unsigned int', but argument 5 has type 'resource_size_t'
>
>
> Each of the lines is something like this:
>
> printk(KERN_DEBUG "PCI: %s reg %x 64bit mmio: [%llx, %llx]\n",
> pci_name(dev), pos, res->start, res->end);
>
> res->start and res->end are resource_size_t (which is phys_addr_t),
> and are sized either 32-bit or 64-bit, based on whether
> CONFIG_PHYS_ADDR_T_64BIT is set.

Oh not those again. Similar warnings in 27-rc's drivers/pci
were fixed recently, but apparently someone out there likes
to create new ones.

The fix is to cast the resource_size_t arguments to unsigned long long.
With "%llx" that's the /only/ valid argument type.

Also note that these warnings aren't harmless. On 32-bit machines
with parameters passed on the stack the mismatch in size between
32-bit resource_size_t and the 64-bit %llx causes undefined
behaviour as printk mis-enumerates its parameters.

/Mikael


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