Messages in this thread | | | From | Arnd Bergmann <> | Date | Wed, 7 Feb 2018 11:33:55 +0100 | Subject | Re: [PATCH] char: nvram: disable on ARM |
| |
On Wed, Feb 7, 2018 at 2:55 AM, Alexandre Belloni <alexandre.belloni@bootlin.com> wrote: > 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.
What about these:
arch/alpha/kernel/rtc.c: spin_lock(&rtc_lock); arch/alpha/kernel/rtc.c: spin_unlock(&rtc_lock); arch/alpha/kernel/time.c:DEFINE_SPINLOCK(rtc_lock); arch/alpha/kernel/time.c:EXPORT_SYMBOL(rtc_lock); arch/arm/kernel/time.c:DEFINE_SPINLOCK(rtc_lock); arch/arm/kernel/time.c:EXPORT_SYMBOL(rtc_lock); arch/m32r/kernel/time.c:DEFINE_SPINLOCK(rtc_lock); arch/m32r/kernel/time.c:EXPORT_SYMBOL(rtc_lock); arch/m68k/atari/time.c:DEFINE_SPINLOCK(rtc_lock); arch/m68k/atari/time.c:EXPORT_SYMBOL_GPL(rtc_lock); arch/mn10300/kernel/rtc.c:DEFINE_SPINLOCK(rtc_lock); arch/mn10300/kernel/rtc.c:EXPORT_SYMBOL(rtc_lock); arch/powerpc/kernel/time.c:DEFINE_SPINLOCK(rtc_lock); arch/powerpc/kernel/time.c:EXPORT_SYMBOL_GPL(rtc_lock); arch/sparc/kernel/time_32.c:DEFINE_SPINLOCK(rtc_lock); arch/sparc/kernel/time_32.c:EXPORT_SYMBOL(rtc_lock); arch/sparc/kernel/time_64.c:DEFINE_SPINLOCK(rtc_lock);
Are they all obsolete?
>> * 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
The thinkpad_acpi driver seems to look at some other bytes in the nvram, which have a platform specific meaning.
For drivers/video/fbdev/, these appear to all be for pre-x86 Apple Macintosh (m68k or powerpc).
Arnd
| |