From 953f00c3ceb5879d8f0d2f2683d70ff93efedad4 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Wed, 21 Feb 2024 14:16:21 +0000 Subject: [PATCH 0908/1085] arm64/Kconfig: Don't set DMA_BOUNCE_UNALIGNED_KMALLOC If enabled, DMA_BOUNCE_UNALIGNED_KMALLOC causes the swiotlb buffers (64MB, by default) to be allocated, even on systems where the DMA controller can reach all of RAM. This is a huge amount of RAM to waste on a device with only 512MB to start with, such as the Zero 2 W. See: https://github.com/raspberrypi/linux/issues/5975 Signed-off-by: Phil Elwell --- arch/arm64/Kconfig | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -122,7 +122,8 @@ config ARM64 select CRC32 select DCACHE_WORD_ACCESS select DYNAMIC_FTRACE if FUNCTION_TRACER - select DMA_BOUNCE_UNALIGNED_KMALLOC + # Disable this to save 64MB when DMA controllers can reach all of RAM + # select DMA_BOUNCE_UNALIGNED_KMALLOC select DMA_DIRECT_REMAP select EDAC_SUPPORT select FRAME_POINTER