Hi,
PCI: map device bus 0, bfd 0x28 bar 0, addr febe0000, size 10000 [mem] bar 1, addr 0, size 20000000 [mem]
Somehow seabios didn't recognise the bar correctly it seems (both 512 and 256 MB cases look the same). For the 256 MB case seabios should have mapped the bar @ 0xe0000000.
... and it should also have figured it is prefetchable memory. Was pci config space messed up somehow? What does 'lspci -v' say once you've booted the machine with linux?
What qemu version you are running? What kind of device is this? Emulated? Code somewhere? Or a real device passed through to the guest?
cheers, Gerd