On 01/10/2014 03:37 AM, Catalin Marinas wrote:
On Thu, Jan 09, 2014 at 09:20:23PM +0000, Al Stone wrote:
On 01/09/2014 10:38 AM, Catalin Marinas wrote:
On 8 January 2014 12:46, Arnd Bergmann <arnd@xxxxxxxx> wrote:
On Wednesday 08 January 2014, al.stone@xxxxxxxxxx wrote:
Even though support for X86 in hardware reduced mode is possible, it
is NOT enabled. Extensive effort has gone into the Linux kernel so that
there is a single kernel image than can run on all x86 hardware; the kernel
changes run-time behavior to adapt to the hardware being used. This is not
currently possible with the existing ACPICA infrastructure but only presents
a problem on achitectures supporting both hardware-reduced and legacy modes
of ACPI -- i.e., on x86 only.
Not sure about the logic here: While it's certainly possible to build a kernel
that runs on all x86 machines, it's also possible to build one that only
runs on some of them when some basic options are turned off. I don't see
any difference between that and what we have on ARM64 or the multiplatform
subset of ARM32.
Would we ever need !CONFIG_ACPI_REDUCED_HARDWARE_ONLY on ARM or ARM64?
If not, we could even make this always on for these archs.
Not that I know of -- and I would hope not. This mode is so much
more straightforward that it makes no sense to me to do anything
but reduced HW if you have the choice.
Thanks for clarifying.
I assume you were thinking of something like this in the arch Kconfig
file:
config ARM64
....
select ACPI_REDUCED_HARDWARE_ONLY if ACPI
...
But, do let me know if you had something else in mind. I think it does
make sense to add so I'll put this in the next version.
The change makes sense but I think it should come with the patches for
ACPI support on arm64 rather than your hw-reduced patches.
Ah. Indeed. That makes more sense; I'll pass it on to my colleagues.
--
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Linaro Enterprise Group
al.stone@xxxxxxxxxx
-----------------------------------
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