| Message ID | 1430259045-19012-2-git-send-email-lho@apm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 28, 2015 at 04:10:41PM -0600, Loc Ho wrote: > --- /dev/null > +++ b/arch/arm64/include/asm/edac.h > @@ -0,0 +1,31 @@ > +/* > + * ARM64 EDAC Header File > + * > + * This program is free software; you can redistribute it and/or modify it > + * under the terms and conditions of the GNU General Public License, > + * version 2, as published by the Free Software Foundation. > + * > + * This program is distributed in the hope it will be useful, but WITHOUT > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or > + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for > + * more details. > + * > + * You should have received a copy of the GNU General Public License along with > + * this program. If not, see <http://www.gnu.org/licenses/>. > + */ > +#ifndef ASM_EDAC_H > +#define ASM_EDAC_H For consistency, please use __ASM_EDAC_H. > +/* > + * ECC atomic, DMA, SMP and interrupt safe scrub function. > + * Implements the per arch atomic_scrub() that EDAC use for software > + * ECC scrubbing. It reads memory and then writes back the original > + * value, allowing the hardware to detect and correct memory errors. > + */ The comment here is misleading since the function doesn't do anything. > +static inline void atomic_scrub(void *va, u32 size) > +{ > + /* Stub function for now until an ARM64 HW has a way to test it. */ > +} Can we have a WARN_ONCE() here? We had some discussions last year, restarted this year and the conclusion was to leave this function as a no-op since it is not safe in the presence of KVM or non-coherent DMA: http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/326986.html
On 04/29/2015 10:40 AM, Catalin Marinas wrote: > On Tue, Apr 28, 2015 at 04:10:41PM -0600, Loc Ho wrote: >> +/* >> + * ECC atomic, DMA, SMP and interrupt safe scrub function. >> + * Implements the per arch atomic_scrub() that EDAC use for software >> + * ECC scrubbing. It reads memory and then writes back the original >> + * value, allowing the hardware to detect and correct memory errors. >> + */ > > The comment here is misleading since the function doesn't do anything. Well, on the other hand, it is "safe" (joke) ;) Suggest a documented few line summary of the status from earlier this year/last year be there instead. Essentially atomic scrubbing is only safe when you're dealing with a fully coherent system. We captured various examples of things that could go wrong in the thread link. > http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/326986.html Thanks Loc and team. Jon.
Hi, >> +/* >> + * ECC atomic, DMA, SMP and interrupt safe scrub function. >> + * Implements the per arch atomic_scrub() that EDAC use for software >> + * ECC scrubbing. It reads memory and then writes back the original >> + * value, allowing the hardware to detect and correct memory errors. >> + */ > > The comment here is misleading since the function doesn't do anything. Okay.. I will leave only this line: ECC atomic, DMA, SMP and interrupt safe scrub function. >> +static inline void atomic_scrub(void *va, u32 size) >> +{ >> + /* Stub function for now until an ARM64 HW has a way to test it. */ >> +} > > Can we have a WARN_ONCE() here? > > We had some discussions last year, restarted this year and the > conclusion was to leave this function as a no-op since it is not safe in > the presence of KVM or non-coherent DMA: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/326986.html I will leave WARN_ONCE. -Loc
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 4269dba..577078f 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -22,6 +22,7 @@ config ARM64 select BUILDTIME_EXTABLE_SORT select CLONE_BACKWARDS select COMMON_CLK + select EDAC_SUPPORT select CPU_PM if (SUSPEND || CPU_IDLE) select DCACHE_WORD_ACCESS select GENERIC_ALLOCATOR diff --git a/arch/arm64/include/asm/edac.h b/arch/arm64/include/asm/edac.h new file mode 100644 index 0000000..1cedba6 --- /dev/null +++ b/arch/arm64/include/asm/edac.h @@ -0,0 +1,31 @@ +/* + * ARM64 EDAC Header File + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef ASM_EDAC_H +#define ASM_EDAC_H + +/* + * ECC atomic, DMA, SMP and interrupt safe scrub function. + * Implements the per arch atomic_scrub() that EDAC use for software + * ECC scrubbing. It reads memory and then writes back the original + * value, allowing the hardware to detect and correct memory errors. + */ +static inline void atomic_scrub(void *va, u32 size) +{ + /* Stub function for now until an ARM64 HW has a way to test it. */ +} + +#endif +
Add an stub atomic_scrub and enable EDAC for arm64. Signed-off-by: Loc Ho <lho@apm.com> --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/edac.h | 31 +++++++++++++++++++++++++++++++ 2 files changed, 32 insertions(+), 0 deletions(-) create mode 100644 arch/arm64/include/asm/edac.h