diff options
| -rw-r--r-- | target/linux/generic/backport-6.6/300-v6.7-arm64-swiotlb-Reduce-the-default-size-if-no-ZONE_DMA.patch | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/target/linux/generic/backport-6.6/300-v6.7-arm64-swiotlb-Reduce-the-default-size-if-no-ZONE_DMA.patch b/target/linux/generic/backport-6.6/300-v6.7-arm64-swiotlb-Reduce-the-default-size-if-no-ZONE_DMA.patch new file mode 100644 index 0000000000..6ede4d32a1 --- /dev/null +++ b/target/linux/generic/backport-6.6/300-v6.7-arm64-swiotlb-Reduce-the-default-size-if-no-ZONE_DMA.patch @@ -0,0 +1,51 @@ +From 65033574ade97afccba074d837fd269903a83a9a Mon Sep 17 00:00:00 2001 +From: Catalin Marinas <catalin.marinas@arm.com> +Date: Thu, 5 Oct 2023 16:40:30 +0100 +Subject: [PATCH] arm64: swiotlb: Reduce the default size if no ZONE_DMA + bouncing needed + +With CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC enabled, the arm64 kernel still +allocates the default SWIOTLB buffer (64MB) even if ZONE_DMA is disabled +or all the RAM fits into this zone. However, this potentially wastes a +non-negligible amount of memory on platforms with little RAM. + +Reduce the SWIOTLB size to 1MB per 1GB of RAM if only needed for +kmalloc() buffer bouncing. + +Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> +Suggested-by: Ross Burton <ross.burton@arm.com> +Cc: Ross Burton <ross.burton@arm.com> +Cc: Will Deacon <will@kernel.org> +Reviewed-by: Robin Murphy <robin.murphy@arm.com> +--- + arch/arm64/mm/init.c | 11 ++++++++++- + 1 file changed, 10 insertions(+), 1 deletion(-) + +--- a/arch/arm64/mm/init.c ++++ b/arch/arm64/mm/init.c +@@ -16,6 +16,7 @@ + #include <linux/nodemask.h> + #include <linux/initrd.h> + #include <linux/gfp.h> ++#include <linux/math.h> + #include <linux/memblock.h> + #include <linux/sort.h> + #include <linux/of.h> +@@ -493,8 +494,16 @@ void __init mem_init(void) + { + bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit); + +- if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC)) ++ if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) { ++ /* ++ * If no bouncing needed for ZONE_DMA, reduce the swiotlb ++ * buffer for kmalloc() bouncing to 1MB per 1GB of RAM. ++ */ ++ unsigned long size = ++ DIV_ROUND_UP(memblock_phys_mem_size(), 1024); ++ swiotlb_adjust_size(min(swiotlb_size_or_default(), size)); + swiotlb = true; ++ } + + swiotlb_init(swiotlb, SWIOTLB_VERBOSE); + |