Re: [PATCH v6 20/20] swiotlb: remove unused SWIOTLB_FORCE flag
From: Petr Tesarik <hidden>
Date: 2026-06-09 13:44:52
Also in:
linux-arm-kernel, linux-coco, linux-iommu, linux-s390, lkml
On Thu, 4 Jun 2026 14:09:59 +0530 "Aneesh Kumar K.V (Arm)" [off-list ref] wrote:
quoted hunk ↗ jump to hunk
SWIOTLB_FORCE has no remaining in-tree users. Forced bouncing is now controlled through the swiotlb=force command line option via swiotlb_force_bounce. Remove the unused flag and simplify the force_bounce initialization. Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org> --- include/linux/swiotlb.h | 1 - kernel/dma/swiotlb.c | 3 +-- 2 files changed, 1 insertion(+), 3 deletions(-)diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 526f82e9da45..af88ca7182f4 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h@@ -15,7 +15,6 @@ struct page; struct scatterlist; #define SWIOTLB_VERBOSE (1 << 0) /* verbose initialization */ -#define SWIOTLB_FORCE (1 << 1) /* force bounce buffering */ #define SWIOTLB_ANY (1 << 2) /* allow any memory for the buffer */
These constants are kernel-internal, so let's not leave a hole in the bitmask... I mean, what about changing SWIOTLB_ANY to (1 << 1) after you remove SWIOTLB_FORCE? Other than that, LGTM. I consider this whole series a big step towards saner handling of encrypted/decrypted memory for DMA buffers. Thank you for your effort! Petr T
quoted hunk ↗ jump to hunk
/*diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index e4bd8c9eaeda..81cc4928e949 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c@@ -400,8 +400,7 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags, if (swiotlb_force_disable) return; - io_tlb_default_mem.force_bounce = - swiotlb_force_bounce || (flags & SWIOTLB_FORCE); + io_tlb_default_mem.force_bounce = swiotlb_force_bounce; #ifdef CONFIG_SWIOTLB_DYNAMIC if (!remap)