From: Florian Fainelli <f.fainelli@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: opendmb@gmail.com, Florian Fainelli <f.fainelli@gmail.com>,
Jonathan Corbet <corbet@lwn.net>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Randy Dunlap <rdunlap@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-doc@vger.kernel.org (open list:DOCUMENTATION),
iommu@lists.linux-foundation.org (open list:SWIOTLB SUBSYSTEM)
Subject: [PATCH] swiotlb: Add swiotlb=off to disable SWIOTLB
Date: Thu, 18 Mar 2021 12:18:14 -0700 [thread overview]
Message-ID: <20210318191816.4185226-1-f.fainelli@gmail.com> (raw)
It may be useful to disable the SWIOTLB completely for testing or when a
platform is known not to have any DRAM addressing limitations what so
ever.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
Documentation/admin-guide/kernel-parameters.txt | 1 +
include/linux/swiotlb.h | 1 +
kernel/dma/swiotlb.c | 9 +++++++++
3 files changed, 11 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 04545725f187..b0223e48921e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5278,6 +5278,7 @@
force -- force using of bounce buffers even if they
wouldn't be automatically used by the kernel
noforce -- Never use bounce buffers (for debugging)
+ off -- Completely disable SWIOTLB
switches= [HW,M68k]
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 5857a937c637..23f86243defe 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -15,6 +15,7 @@ enum swiotlb_force {
SWIOTLB_NORMAL, /* Default - depending on HW DMA mask etc. */
SWIOTLB_FORCE, /* swiotlb=force */
SWIOTLB_NO_FORCE, /* swiotlb=noforce */
+ SWIOTLB_OFF, /* swiotlb=off */
};
/*
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index c10e855a03bc..d7a4a789c7d3 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -126,6 +126,8 @@ setup_io_tlb_npages(char *str)
} else if (!strcmp(str, "noforce")) {
swiotlb_force = SWIOTLB_NO_FORCE;
io_tlb_nslabs = 1;
+ } else if (!strcmp(str, "off")) {
+ swiotlb_force = SWIOTLB_OFF;
}
return 0;
@@ -229,6 +231,9 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
unsigned long i, bytes;
size_t alloc_size;
+ if (swiotlb_force == SWIOTLB_OFF)
+ return 0;
+
bytes = nslabs << IO_TLB_SHIFT;
io_tlb_nslabs = nslabs;
@@ -284,6 +289,9 @@ swiotlb_init(int verbose)
unsigned char *vstart;
unsigned long bytes;
+ if (swiotlb_force == SWIOTLB_OFF)
+ goto out;
+
if (!io_tlb_nslabs) {
io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
@@ -302,6 +310,7 @@ swiotlb_init(int verbose)
io_tlb_start = 0;
}
pr_warn("Cannot allocate buffer");
+out:
no_iotlb_memory = true;
}
--
2.25.1
next reply other threads:[~2021-03-18 19:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-18 19:18 Florian Fainelli [this message]
2021-03-18 19:22 ` [PATCH] swiotlb: Add swiotlb=off to disable SWIOTLB Florian Fainelli
2021-03-18 19:34 ` Robin Murphy
2021-03-18 19:43 ` Florian Fainelli
2021-03-18 19:53 ` Robin Murphy
2021-03-18 21:31 ` Florian Fainelli
2021-03-18 23:35 ` Robin Murphy
2021-03-19 0:48 ` Florian Fainelli
2021-03-19 2:34 ` Konrad Rzeszutek Wilk
2021-03-19 4:00 ` [PATCH] swiotlb: Make SWIOTLB_NO_FORCE perform no allocation Florian Fainelli
2021-03-19 5:01 ` Konrad Rzeszutek Wilk
2021-03-21 3:37 ` [PATCH v2] " Florian Fainelli
2021-03-22 7:46 ` Christoph Hellwig
2021-03-23 1:53 ` [PATCH v3] " Florian Fainelli
2021-03-24 8:42 ` Christoph Hellwig
2021-04-09 3:13 ` Florian Fainelli
2021-04-09 19:32 ` Konrad Rzeszutek Wilk
2021-04-09 20:33 ` Florian Fainelli
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