On 01/06/2015 05:06 PM, Jon Masters wrote:
Hi Arnd,
Happy New Year!
On 01/06/2015 02:21 PM, Arnd Bergmann wrote:
On Tuesday 06 January 2015 11:24:43 Jon Masters wrote:
On 01/06/2015 06:20 AM, Catalin Marinas wrote:
Now, what's preventing a vendor firmware from providing only ACPI tables? Do we enforce it in some way (arm-acpi.txt, kernel warning etc.) that both DT and ACPI are supported, or at least that dts files are merged in the kernel first?
I know of some (server) firmware that will only provide ACPI in the medium term, so this is coming.
Medium term is fine, as long as they are not expecting their hardware to be supported by Linux before ACPI support is stable enough for general consumption.
To be clear, I think that's reasonable for upstream. I may love ACPI, but vendors can always ship kernels with a config supporting ACPI only platforms in the interim period if they have a commercial justification and that doesn't have to be supported in terms of the upstream default.
But, perhaps there's a way to have it both ways, you could consider also a CONFIG_EXPERT option that would allow you to build a kernel with ACPI only support in the medium term. That way, if someone is running a vendor kernel, but wants to track upstream development more closely, they can do so on such hardware by enabling the expert config bit.
Clarification: I'm suggesting that in the medium term the dependency upon CONFIG_EXPERT either goes away or is replaced with requiring ACPI and DTB in the non "expert" case and requiring "expert" selected to allow a kernel that will boot with ACPI only. But only a suggestion.
Jon.