[PATCH v5 1/5] ACPI: introduce CONFIG_ACPI_REDUCED_HARDWARE_ONLY to enforce this ACPI mode
From: Al Stone <hidden>
Date: 2014-01-10 17:12:32
Also in:
linux-acpi
On 01/10/2014 03:37 AM, Catalin Marinas wrote:
On Thu, Jan 09, 2014 at 09:20:23PM +0000, Al Stone wrote:quoted
On 01/09/2014 10:38 AM, Catalin Marinas wrote:quoted
On 8 January 2014 12:46, Arnd Bergmann [off-list ref] wrote:quoted
On Wednesday 08 January 2014, al.stone at linaro.org wrote:quoted
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.quoted
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 at linaro.org -----------------------------------