Hi Stefano,
On 02/16/2017 01:41 AM, Stefano Stabellini wrote:
On Fri, 3 Feb 2017, Julien Grall wrote:
On ARM, when the user put 'acpi=force' Xen will use ACPI over DT.
Currently, if Xen fails to initialize ACPI it will fallback on DT.
This behavior makes difficult for a user to notice Xen didn't used ACPI
has requested on platform where the firmware is providing both ACPI and DT.
Rather than fallback on DT during a failure, panic when 'acpi=force'.
Signed-off-by: Julien Grall <julien.gr...@arm.com>
---
I am wondering if we should do the same with acpi=on. So a user
would notice directly if something went wrong with ACPI.
Otherwise you would boot up to the prompt and barely notice that DT
was used.
I would keep the current behavior as is and add new parameter that means
"acpi and only acpi". Today acpi=force means "acpi is preferred to
device tree". It doesn't mean that if acpi fail, Xen should panic.
Maybe acpi=strict or acpi=mandatory?
We have a bunch of option that makes little sense today:
- off: Turned off ACPI
- on: Turned on ACPI only if DT is empty
- force: Turned on ACPI
If ACPI fails you fallback on DT. This is a pain to detect whether DT or
ACPI is been used. So I think adding another option will only confuse
the user.
Looking at Linux the option are:
- off: Turned off ACPI
- on: Prefer ACPI over DT. Fallback on DT is failed
- force: Use ACPI and panic if not available
I would much prefer to use the behavior of the acpi param on Linux
because it will avoid the user to be confused on the usage.
Cheers,
--
Julien Grall
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