This reverts commit 0cf8882fd06ba0aeb1e90fa6f23fce85504d7e14.
Which this commit, with aarch64 when using efi PCI devices with IO ports
do not work. The reason is that EFI creates I/O port mappings below
0x1000 (in fact, at 0). However Linux, for legacy reasons, does not
support I/O ports <= 0x1000 on PCI, so the I/O assignment created by EFI
is rejected.
EFI creates the mappings primarily for itself, and up until DSM #5
started to be enforced, all PCI resource allocations that existed at
boot were ignored by Linux and recreated from scratch.
Also, the commit in question looks dubious - it seems unlikely that
Linux would fail to create a resource tree. What does
happen is that BARs get moved around, which may cause trouble in some
cases: for instance, Linux had to add special code to the EFI framebuffer
driver to copy with framebuffer BARs being relocated.
DSM #5 has a long history of debate and misinterpretation.
Link: https://lore.kernel.org/r/20210724185234.GA2265457@roeck-us.net/
Fixes: 0cf8882fd06 ("acpi/gpex: Inform os to keep firmware resource map")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
40c3472a29