Linux reads some ACPI registers from interrupt context. For example,
we read the PM1 Status register in the SCI interrupt handler via
this path:
acpi_irq
acpi_ev_sci_xrupt_handler
acpi_ev_fixed_event_detect
acpi_hw_register_read
acpi_hw_read_multiple
acpi_read
But acpi_read() takes a generic address structure, and if that
address happens to be in memory space (not I/O port space), we use
acpi_os_read_memory(). In Linux, that uses ioremap() to map the
address, and that doesn't work from interrupt context.
I can imagine fixing this by doing the ioremap() at boot-time
rather than at interrupt-time, but most of this interrupt path
is in the ACPI CA, not in Linux itself, so it would probably
require some redesign in the CA.
Any suggestions?
Bjorn
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