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SubjectRe: [PATCH] Remove CONFIG_PM altogether, enable power management all the time

* Rafael J. Wysocki <rjw@sisk.pl> wrote:

> I'd appreciate it if people could review/test it and drop their comments.
>
> Thanks,
> Rafael
>
> ---
> arch/x86/xen/Kconfig | 2 +-
> drivers/acpi/Kconfig | 1 -
> drivers/acpi/bus.c | 4 +---
> drivers/acpi/internal.h | 6 ++++++
> drivers/acpi/sleep.c | 13 +++++++++++--
> drivers/base/power/Makefile | 3 +--
> drivers/net/e1000e/netdev.c | 8 ++++----
> drivers/net/pch_gbe/pch_gbe_main.c | 2 +-
> drivers/pci/pci-driver.c | 4 ++--
> drivers/scsi/Makefile | 2 +-
> drivers/scsi/scsi_priv.h | 2 +-
> drivers/scsi/scsi_sysfs.c | 2 +-
> drivers/usb/core/hcd-pci.c | 4 ++--
> include/acpi/acpi_bus.h | 2 +-
> include/linux/pm.h | 2 +-
> kernel/power/Kconfig | 29 +++--------------------------
> 16 files changed, 37 insertions(+), 49 deletions(-)

Ok, there's some real bang for bucks in this patch, nice! It's a beginning.

Reviewed-by: Ingo Molnar <mingo@elte.hu>

Also, i've Cc:-ed Linus, to check whether the idea to make power management a
permanent, core portion of Linux has any obvious downsides we missed.

Rafael, could you do a defconfig-ish x86 build with and without CONFIG_PM, and post
the 'size vmlinux' comparison - so that we can see the size difference? We make some
things CONFIG_EXPERT configurable just to enable folks who *really* want to cut down
on kernel size to configure it out.

Note that those usecases, even if they want a super-small kernel, might not care
about PM at all while they care about size: small boot kernels in ROMs, or simple
devices where CPU-idling implies deep low power mode, etc.

So the vmlinux size comparisons would be needed really. If it's 5k nobody will care.
If it's 50k-100k that's borderline. In the other side of the scale we have the 1500+
#ifdef CONFIG_PM lines strewn around the kernel source, and the frequent !PM build
breakages.

Ingo


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