The patch titled
x86: allow CONFIG_ISA_DMA_API to be disabled
has been added to the -mm tree. Its filename is
x86-allow-config_isa_dma_api-to-be-disabled.patch
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Subject: x86: allow CONFIG_ISA_DMA_API to be disabled
From: David Rientjes <rientjes@xxxxxxxxxx>
Not all 64-bit systems require ISA-style DMA, so allow it to be
configurable. x86 utilizes the generic ISA DMA allocator from
kernel/dma.c, so require it only when CONFIG_ISA_DMA_API is enabled.
Disabling CONFIG_ISA_DMA_API is dependent on x86_64 since those machines
do not have ISA slots and benefit the most from disabling the option (and
on CONFIG_EXPERT as required by H. Peter Anvin).
When disabled, this also avoids declaring claim_dma_lock(),
release_dma_lock(), request_dma(), and free_dma() since those interfaces
will no longer be provided.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Bjorn Helgaas <bjorn.helgaas@xxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: "Luck, Tony" <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 10 +++++++---
arch/x86/include/asm/dma.h | 6 +++++-
2 files changed, 12 insertions(+), 4 deletions(-)
diff -puN arch/x86/Kconfig~x86-allow-config_isa_dma_api-to-be-disabled arch/x86/Kconfig
--- a/arch/x86/Kconfig~x86-allow-config_isa_dma_api-to-be-disabled
+++ a/arch/x86/Kconfig
@@ -120,7 +120,7 @@ config NEED_SG_DMA_LENGTH
def_bool y
config GENERIC_ISA_DMA
- def_bool y
+ def_bool ISA_DMA_API
config GENERIC_IOMAP
def_bool y
@@ -2001,9 +2001,13 @@ source "drivers/pci/pcie/Kconfig"
source "drivers/pci/Kconfig"
-# x86_64 have no ISA slots, but do have ISA-style DMA.
+# x86_64 have no ISA slots, but can have ISA-style DMA.
config ISA_DMA_API
- def_bool y
+ bool "ISA-style DMA support" if (X86_64 && EXPERT)
+ default y
+ help
+ Enables ISA-style DMA support for devices requiring such controllers.
+ If unsure, say Y.
if X86_32
diff -puN arch/x86/include/asm/dma.h~x86-allow-config_isa_dma_api-to-be-disabled arch/x86/include/asm/dma.h
--- a/arch/x86/include/asm/dma.h~x86-allow-config_isa_dma_api-to-be-disabled
+++ a/arch/x86/include/asm/dma.h
@@ -151,6 +151,7 @@
#define DMA_AUTOINIT 0x10
+#ifdef CONFIG_ISA_DMA_API
extern spinlock_t dma_spin_lock;
static inline unsigned long claim_dma_lock(void)
@@ -164,6 +165,7 @@ static inline void release_dma_lock(unsi
{
spin_unlock_irqrestore(&dma_spin_lock, flags);
}
+#endif /* CONFIG_ISA_DMA_API */
/* enable/disable a specific DMA channel */
static inline void enable_dma(unsigned int dmanr)
@@ -303,9 +305,11 @@ static inline int get_dma_residue(unsign
}
-/* These are in kernel/dma.c: */
+/* These are in kernel/dma.c because x86 uses CONFIG_GENERIC_ISA_DMA */
+#ifdef CONFIG_ISA_DMA_API
extern int request_dma(unsigned int dmanr, const char *device_id);
extern void free_dma(unsigned int dmanr);
+#endif
/* From PCI */
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
x86-numa-add-error-handling-for-bad-cpu-to-node-mappings.patch
oom-suppress-nodes-that-are-not-allowed-from-meminfo-on-oom-kill.patch
oom-suppress-show_mem-for-many-nodes-in-irq-context-on-page-alloc-failure.patch
oom-suppress-nodes-that-are-not-allowed-from-meminfo-on-page-alloc-failure.patch
pnp-only-assign-ioresource_dma-if-config_isa_dma_api-is-enabled.patch
x86-only-compile-8237a-if-config_isa_dma_api-is-enabled.patch
x86-only-compile-floppy-driver-if-config_isa_dma_api-is-enabled.patch
x86-allow-config_isa_dma_api-to-be-disabled.patch
jbd-remove-dependency-on-__gfp_nofail.patch
memcg-res_counter_read_u64-fix-potential-races-on-32-bit-machines.patch
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