When Linus remaps IRQ0 on x86, I'll follow that code as a testament. Until 
this happens, I consider is just an opinion. Forcing every arch but x86 to 
remap IRQ0 is an example of the double standards.

Yawn.. x86 does not expose IRQ 0 outside of arch specific code.
 

quoted

The checks need pushing upwards and removing from their current place -
the pci layer should check the resource length, the isa pnp should I
believe check for zero address etc.

    So, it's OK to remove the base *address* check in ide_hwif_confiure() 
altogether?

IFF you move all the other checks, verify their correctness and then get
them tested for a while yes
 

quoted

libata makes a similar assumption in ata_resources_present() as someone
(GregKH ???) needs to define what the proper way to encode "resource not
allocated" into the PCI resources should be.

quoted

If someone on the PCI list (cc'd) or Greg can give a definitive answer then we can go fix the
offenders now.

    Well, I thought that was IORESOURCE_UNSET...

It seems to depend which line of code you ask - hence the question 8(