When testing e1000 with the virt machine, e1000's I/O space cannot
be accessed. Debugging shows that the I/O BAR (BAR1) is correctly
written with address 0 plus I/O enable bit, but QEMU's "info pci"
shows that:
Bus 0, device 1, function 0:
Ethernet controller: PCI device 8086:100e
...
BAR1: I/O at 0xffffffffffffffff [0x003e].
...
It turns out we should set pci_allow_0_address to true to allow 0
PCI address, otherwise pci_bar_address() treats such address as
PCI_BAR_UNMAPPED.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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