On 06/02/2018 at 23:55:02 +0100, Arnd Bergmann wrote: > * arch/arm/kernel/time.c has this code > > #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \ > defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE) > /* this needs a better home */ > DEFINE_SPINLOCK(rtc_lock); > EXPORT_SYMBOL(rtc_lock); > #endif /* pc-style 'CMOS' RTC support */ > > That can be adapted now, or maybe we could move all definitions into > a common place (that needs some more planning). >
Yes, on arm, the rtc_lock is mostly there to please drivers/rtc/rtc-cmos.c. Maybe we could make the locking in this driver x86 and PPC specific. If we can get rid of arch/powerpc/platforms/chrp/time.c and arch/powerpc/platforms/maple/time.c (so much duplicated code), then it is x86 only. > * similarly, this line in nvram.c can be simplified: > #if defined(CONFIG_ATARI) > # define MACH ATARI > #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) /* and ?? > */ > # define MACH PC > #else > # error Cannot build nvram driver for this machine configuration. > #endif > > * GENERIC_NVRAM is not really generic, instead this seems to be the > chardev that is used for 32-bit powerpc (powermac, 85xx, 86xx), while > 64-bit powerpc (cell, maple, opal, pseries) use code from > arch/powerpc/kernel/nvram_64.c, with the same underlying arch hooks. > The nvram_64 code appears to be mostly a superset of the 32-bit > generic_nvram one. > > * The code in drivers/char/nvram is not used at all when > GENERIC_NVRAM is set, and half the code in there is different > between x86 and atari. > > * most of the external interface in include/linux/nvram.h is > unused, the rest tends to be architecture specific > > * The procfs file appears to be completely useless on any 64-bit > x86 machine, this is what I see: > > $ cat /proc/driver/nvram > Checksum status: valid > # floppies : 0 > Floppy 0 type : none > Floppy 1 type : none > HD 0 type : none > HD 1 type : none > HD type 48 data: 0/0/0 C/H/S, precomp 0, lz 0 > HD type 49 data: 156/0/0 C/H/S, precomp 0, lz 0 > DOS base memory: 635 kB > Extended memory: 65535 kB (configured), 65535 kB (tested) > Gfx adapter : EGA, VGA, ... (with BIOS) > FPU : not installed > I really don't think anyone is using that but I don't really know much about x86 and the specification this may be part of. I see the info may be used in drivers/video/fbdev/ and drivers/platform/x86/thinkpad_acpi.c -- Alexandre Belloni, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering http://bootlin.com
