From a149cf00b158e1793a8dd89ca492379c366300d2 Mon Sep 17 00:00:00 2001 From: Zhen Lei Date: Wed, 16 Nov 2022 20:10:43 +0800 Subject: arm64: kdump: Provide default size when crashkernel=Y,low is not specified Try to allocate at least 128 MiB low memory automatically for the case that crashkernel=,high is explicitly specified, while crashkenrel=,low is omitted. This allows users to focus more on the high memory requirements of their business rather than the low memory requirements of the crash kernel booting. Signed-off-by: Zhen Lei Acked-by: Baoquan He Reviewed-by: Catalin Marinas Link: https://lore.kernel.org/r/20221116121044.1690-2-thunder.leizhen@huawei.com Signed-off-by: Will Deacon --- Documentation/admin-guide/kernel-parameters.txt | 13 +++++-------- arch/arm64/mm/init.c | 8 ++++++-- 2 files changed, 11 insertions(+), 10 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a465d5242774..6c6fafc3fba9 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -851,26 +851,23 @@ 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 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 requires at least 64M+32K low memory, also enough extra low memory is needed to make sure DMA buffers for 32-bit devices won't run out. Kernel would try to allocate - at least 256M below 4G automatically. + default size of memory below 4G automatically. The default + size is platform dependent. + --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB) + --> arm64: 128MiB This one lets the user specify own low range under 4G for second kernel instead. 0: to disable low allocation. 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 4b4651ee47f2..ba7227179822 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -96,6 +96,8 @@ 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) +#define DEFAULT_CRASH_KERNEL_LOW_SIZE (128UL << 20) + static int __init reserve_crashkernel_low(unsigned long long low_size) { unsigned long long low_base; @@ -147,7 +149,9 @@ 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; @@ -170,7 +174,7 @@ static void __init reserve_crashkernel(void) return; } - if ((crash_base >= CRASH_ADDR_LOW_MAX) && + if ((crash_base > CRASH_ADDR_LOW_MAX - crash_low_size) && crash_low_size && reserve_crashkernel_low(crash_low_size)) { memblock_phys_free(crash_base, crash_size); return; -- cgit v1.2.3