Messages in this thread | | | Subject | Re: [PATCH] irqchip/gic-v3-its: Add early memory allocation errata | From | Marc Zyngier <> | Date | Fri, 5 Oct 2018 11:55:48 +0100 |
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Hi Matthias,
On 04/10/18 23:11, Matthias Brugger wrote: > Friendly reminder, if anyone has any comment on the patch :) > > On 9/12/18 11:52 AM, matthias.bgg@kernel.org wrote: >> From: Matthias Brugger <mbrugger@suse.com> >> >> Some hardware does not implement two-level page tables so that >> the amount of contigious memory needed by the baser is bigger >> then the zone order. This is a known problem on Cavium Thunderx >> with 4K page size. >> >> We fix this by adding an errata which allocates the memory early >> in the boot cycle, using the memblock allocator. >> >> Signed-off-by: Matthias Brugger <mbrugger@suse.com> >> --- >> arch/arm64/Kconfig | 12 ++++++++ >> arch/arm64/include/asm/cpucaps.h | 3 +- >> arch/arm64/kernel/cpu_errata.c | 33 +++++++++++++++++++++ >> drivers/irqchip/irq-gic-v3-its.c | 50 ++++++++++++++++++++------------ >> 4 files changed, 79 insertions(+), 19 deletions(-)
My only comment would be to state how much I dislike both the HW and the patch... ;-) The idea that we have some erratum that depends on the page size doesn't feel good at all.
>> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 1b1a0e95c751..dfd9fe08f0b2 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -597,6 +597,18 @@ config QCOM_FALKOR_ERRATUM_E1041 >> >> If unsure, say Y. >> >> +config CAVIUM_ALLOC_ITS_TABLE_EARLY >> + bool "Cavium Thunderx: Allocate the its table early" >> + default y >> + depends on ARM64_4K_PAGES && FORCE_MAX_ZONEORDER < 13
Here's a though: Why don't we ensure that FORCE_MAX_ZONEORDER is such as we could always allocate the same amount of memory, no matter what the page size is? That, or bump FORCE_MAX_ZONEORDER to 13 if the kernel includes support for TX1.
Any of this of course requires buy-in from the arm64 maintainers, as this is quite a departure from the way things work so far.
Thanks,
M. -- Jazz is not dead. It just smells funny...
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