mp_machdep.c (was Re: [Fwd: Re: Bug reports requested - acpi])

Nate Lawson nate at
Tue Sep 21 13:23:30 PDT 2004

John Baldwin wrote:
> On Tuesday 21 September 2004 01:10 pm, Nate Lawson wrote:
>>A quick "no" vote from me until this is really understood.  I think the
>>real problem is an interference between the pmap for the AP trampoline
>>and the acpi wake code (sys/i386/acpica/acpi_wakeup.c).  The address you
>>gave (0x9f000) is right before the base address we use for the wakeup
>>code (0xa0000).  As I woke up this morning, I was wondering if this
>>could be the issue.  An easy way to test is to disable the call to
>>acpi_install_wakeup_handler() in sys/i386/acpica/acpi_machdep.c and see
>>if this alone fixes the problem.
>>If I'm wrong, feel free to commit your patch.
>>P.S. Spaces instead of tabs in your diff.
> Umm, 0xa0000 is the start of Video RAM, so I sure hope the ACPI wake code 
> doesn't try to write code into Video memory.  The pmap_invalidate_page is 
> certainly needed.

This call to alloc the memory seems to say 0xa0000 is the first valid 
start address:

if (bus_dma_tag_create(/* parent */ NULL, /* alignment */ 2, 0,
     /* lowaddr below 1MB */ 0x9ffff,
     /* highaddr */ BUS_SPACE_MAXADDR, NULL, NULL,
     PAGE_SIZE, 1, PAGE_SIZE, 0, busdma_lock_mutex,
     &Giant, &acpi_waketag) != 0)

In any case, you're right about needing to invalidate the mapping after 
creating it so feel free to commit.  Do we also need this after 
pmap_enter() in acpi_sleep_machdep() (i386/acpica/acpi_wakeup.c)?


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