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sun4u: remap ebus BAR0 to use unassigned_io_ops instead of alias to PCI IO space

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During kernel startup OpenBSD accesses addresses mapped by BAR0 of the ebus device
but at offsets where no IO devices exist. Before commit 4aa07e8649 ("hw/sparc64/ebus:
Access memory regions via pci_address_space_io()") BAR0 was mapped to legacy IO
space which allows accesses to unmapped devices to succeed, but afterwards these
accesses to unmapped PCI IO space cause a memory fault which prevents OpenBSD from
booting.

Since no devices are mapped at the addresses accessed by OpenBSD, change ebus BAR0
from a PCI IO space alias to an IO memory region using unassigned_io_ops which allows
these accesses to succeed and so allows OpenBSD to boot once again.

Fixes: 4aa07e8649 ("hw/sparc64/ebus: Access memory regions via pci_address_space_io()")
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240311064345.2531197-1-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
This commit is contained in:
Mark Cave-Ayland 2024-03-11 06:43:45 +00:00 committed by Philippe Mathieu-Daudé
parent b691b250d3
commit c1c73b31d9
1 changed files with 7 additions and 2 deletions
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9
hw/sparc64/sun4u.c
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@ -360,8 +360,13 @@ static void ebus_realize(PCIDevice *pci_dev, Error **errp)
pci_dev->config[0x09] = 0x00; // programming i/f
pci_dev->config[0x0D] = 0x0a; // latency_timer
memory_region_init_alias(&s->bar0, OBJECT(s), "bar0",
pci_address_space_io(pci_dev), 0, 0x1000000);
/*
* BAR0 is accessed by OpenBSD but not for ebus device access: allow any
* memory access to this region to succeed which allows the OpenBSD kernel
* to boot.
*/
memory_region_init_io(&s->bar0, OBJECT(s), &unassigned_io_ops, s,
"bar0", 0x1000000);
pci_register_bar(pci_dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->bar0);
memory_region_init_alias(&s->bar1, OBJECT(s), "bar1",
pci_address_space_io(pci_dev), 0, 0x8000);