Re: [Xen-devel] [PATCH] acpi: Switch to dynamic mapping at SYS_STATE_boot

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 31.01.17 at 17:05, <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 01/31/2017 10:56 AM, Jan Beulich wrote:
>>>>> On 31.01.17 at 16:52, <boris.ostrovsky@xxxxxxxxxx> wrote:
>>> On 01/31/2017 06:01 AM, Jan Beulich wrote:
>>>>>>> On 30.01.17 at 19:26, <boris.ostrovsky@xxxxxxxxxx> wrote:
>>>>> We can switch ACPI from using fixmap to dynamic mapping as soon as
>>>>> the system enters SYS_STATE_boot. This will allow us, for example,
>>>>> to map MADT on systems with large number of processors where the
>>>>> table might not fit into NUM_FIXMAP_ACPI_PAGES (currently set to 4).
>>>> I think this needs a little more care. While ARM switches to
>>>> SYS_STATE_boot after having called vm_init(), that's not the case
>>>> on x86. Granted there's no ACPI code being invoked in between,
>>>> but this would still be a latent bug (as soon as someone inserts any
>>>> code there).
>>> Then acpi_os_map_memory() shouldn't rely on system_state at all.
>> Why?
> 
> Because it really is only interested in whether vm_init() has been
> called, nor what the overall system state is (even if vmap status can be
> implied from the state).
> 
> But I can swap the two if you prefer that.

Seems better to me than introducing vm_ready(). But perhaps
others are of differing opinion...

Jan


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