On Mon, Dec 23, 2019 at 8:57 PM Chen Zhou <chenzhou10@xxxxxxxxxx> wrote: > > Crashkernel=X tries to reserve memory for the crash dump kernel under > 4G. If crashkernel=X,low is specified simultaneously, reserve spcified > size low memory for crash kdump kernel devices firstly and then reserve > memory above 4G. > > Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx> > --- > arch/arm64/kernel/setup.c | 8 +++++++- > arch/arm64/mm/init.c | 31 +++++++++++++++++++++++++++++-- > 2 files changed, 36 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > index 56f6645..04d1c87 100644 > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -238,7 +238,13 @@ static void __init request_standard_resources(void) > kernel_data.end <= res->end) > request_resource(res, &kernel_data); > #ifdef CONFIG_KEXEC_CORE > - /* Userspace will find "Crash kernel" region in /proc/iomem. */ > + /* > + * Userspace will find "Crash kernel" region in /proc/iomem. > + * Note: the low region is renamed as Crash kernel (low). > + */ > + if (crashk_low_res.end && crashk_low_res.start >= res->start && > + crashk_low_res.end <= res->end) > + request_resource(res, &crashk_low_res); > if (crashk_res.end && crashk_res.start >= res->start && > crashk_res.end <= res->end) > request_resource(res, &crashk_res); > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index b65dffd..0d7afd5 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -80,6 +80,7 @@ static void __init reserve_crashkernel(void) > { > unsigned long long crash_base, crash_size; > int ret; > + phys_addr_t crash_max = arm64_dma32_phys_limit; > > ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), > &crash_size, &crash_base); > @@ -87,12 +88,38 @@ static void __init reserve_crashkernel(void) > if (ret || !crash_size) > return; > > + ret = reserve_crashkernel_low(); > + if (!ret && crashk_low_res.end) { > + /* > + * If crashkernel=X,low specified, there may be two regions, > + * we need to make some changes as follows: > + * > + * 1. rename the low region as "Crash kernel (low)" > + * In order to distinct from the high region and make no effect > + * to the use of existing kexec-tools, rename the low region as > + * "Crash kernel (low)". > + * > + * 2. change the upper bound for crash memory > + * Set MEMBLOCK_ALLOC_ACCESSIBLE upper bound for crash memory. > + * > + * 3. mark the low region as "nomap" > + * The low region is intended to be used for crash dump kernel > + * devices, just mark the low region as "nomap" simply. > + */ > + const char *rename = "Crash kernel (low)"; > + > + crashk_low_res.name = rename; > + crash_max = MEMBLOCK_ALLOC_ACCESSIBLE; > + memblock_mark_nomap(crashk_low_res.start, > + resource_size(&crashk_low_res)); > + } > + > crash_size = PAGE_ALIGN(crash_size); > > if (crash_base == 0) { > /* Current arm64 boot protocol requires 2MB alignment */ > - crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit, > - crash_size, SZ_2M); > + crash_base = memblock_find_in_range(0, crash_max, crash_size, > + SZ_2M); > if (crash_base == 0) { > pr_warn("cannot allocate crashkernel (size:0x%llx)\n", > crash_size); > -- I tested this patch series on ARM64-ThunderX2 with no issue with bootargs crashkenel=X@Y crashkernel=250M,low $ dmesg | grep crash [ 0.000000] crashkernel reserved: 0x0000000b81200000 - 0x0000000c81200000 (4096 MB) [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+ root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro crashkernel=4G@0xb81200000 crashkernel=250M,low nowatchdog earlycon [ 29.310209] crashkernel=250M,low $ kexec -p -i /boot/vmlinuz-`uname -r` --initrd=/boot/initrd.img-`uname -r` --reuse-cmdline $ echo 1 > /proc/sys/kernel/sysrq ; echo c > /proc/sysrq-trigger But when i tried with crashkernel=4G crashkernel=250M,low as bootargs. Kernel is not able to allocate memory. [ 0.000000] cannot allocate crashkernel (size:0x100000000) [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+ root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro crashkernel=4G crashkernel=250M,low nowatchdog [ 29.332081] crashkernel=250M,low does crashkernel=X@Y mandatory to get allocated beyond 4G? am I missing something? --pk _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec