On 2022/6/17 10:40, Baoquan He wrote:
On 06/13/22 at 04:09pm, Zhen Lei wrote:
quoted
To be consistent with the implementation of x86 and improve cross-platform
user experience. Try to allocate at least 256 MiB low memory automatically
when crashkernel=Y,low is not specified.
This should correspond to the case that crashkernel=,high is explicitly
specified, while crashkenrel=,low is omitted. It could be better to
mention these.
Okay, I'll update the description in the next version.
Otherwise, this looks good to me.
quoted
Signed-off-by: Zhen Lei <redacted>
---
Documentation/admin-guide/kernel-parameters.txt | 8 +-------
arch/arm64/mm/init.c | 12 +++++++++++-
2 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 8090130b544b070..61b179232b68001 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -843,7 +843,7 @@
available.
It will be ignored if crashkernel=X is specified.
crashkernel=size[KMG],low
- [KNL, X86-64] range under 4G. When crashkernel=X,high
+ [KNL, X86-64, ARM64] range under 4G. When crashkernel=X,high
~~~~ exceeds 80 characters, it should be OK.
quoted
is passed, kernel could allocate physical memory region
above 4G, that cause second kernel crash on system
that require some amount of low memory, e.g. swiotlb
@@ -857,12 +857,6 @@
It will be ignored when crashkernel=X,high is not used
or memory reserved is below 4G.
- [KNL, ARM64] range in low memory.
- This one lets the user specify a low range in the
- DMA zone for the crash dump kernel.
- It will be ignored when crashkernel=X,high is not used
- or memory reserved is located in the DMA zones.
-
cryptomgr.notests
[KNL] Disable crypto self-tests
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 339ee84e5a61a0b..5390f361208ccf7 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -96,6 +96,14 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit = PHYS_MASK + 1;
#define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit
#define CRASH_ADDR_HIGH_MAX (PHYS_MASK + 1)
+/*
+ * This is an empirical value in x86_64 and taken here directly. Please
+ * refer to the code comment in reserve_crashkernel_low() of x86_64 for more
+ * details.
+ */
+#define DEFAULT_CRASH_KERNEL_LOW_SIZE \
+ max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20)
+
static int __init reserve_crashkernel_low(unsigned long long low_size)
{
unsigned long long low_base;@@ -147,7 +155,9 @@ static void __init reserve_crashkernel(void)
* is not allowed.
*/
ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base);
- if (ret && (ret != -ENOENT))
+ if (ret == -ENOENT)
+ crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
+ else if (ret)
return;
crash_max = CRASH_ADDR_HIGH_MAX;
--
2.25.1
.
--
Regards,
Zhen Lei
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