Re: [PATCH v7 2/4] arm64: kdump: reserve crashkenel above 4G for crash dump kernel
From: Prabhakar Kushwaha
Date: Tue Mar 10 2020 - 13:09:24 EST
On 3/10/2020 7:00 AM, chenzhou wrote:
> Hi,
>
> On 2020/3/9 23:51, Prabhakar Kushwaha wrote:
>> On 3/9/2020 10:18 AM, Prabhakar Kushwaha wrote:
>>> Hi Chen,
>>>
>>> On Sat, Mar 7, 2020 at 4:36 PM Chen Zhou <chenzhou10@xxxxxxxxxx> wrote:
>>>>
>>>>
>>>>
>>>> On 2020/3/5 18:13, Prabhakar Kushwaha wrote:
>>>>> 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?
>>>>
>>>> I can't reproduce the problem in my environment, can you test with other size,
>>>> such as "crashkernel=1G crashkernel=250M,low", see if there is the same issue.
>>>>
>>> I tried 1G also. Same error, please find the logs
>>>
>>> $ dmesg | grep crash
>>> [ 0.000000] cannot allocate crashkernel (size:0x40000000)
>>> [ 0.000000] Kernel command line:
>>> BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
>>> root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro nowatchdog earlycon
>>> crashkernel=1G crashkernel=250M,low
>>> [ 29.326916] crashkernel=250M,low
>>>
>>>
>>>> Besides, crashkernel=X@Y isn't mandatory to get allocated beyond 4G,
>>>
>>> this was my understanding also.
>>>
>>>> can you show the whole file /proc/iomem.
>>>>
>>>
>>> $ cat /proc/iomem
>>> 00000000-00000000 : PCI ECAM
>>> 00000000-00000000 : PCI ECAM
>>> 00000000-00000000 : PCI Bus 0000:00
>>> 00000000-00000000 : PCI Bus 0000:0f
>>> 00000000-00000000 : PCI Bus 0000:10
>>> 00000000-00000000 : 0000:10:00.0
>>> 00000000-00000000 : 0000:10:00.0
>>> 00000000-00000000 : PCI Bus 0000:01
>>> 00000000-00000000 : 0000:01:00.0
>>> 00000000-00000000 : 0000:01:00.1
>>> 00000000-00000000 : PCI Bus 0000:05
>>> 00000000-00000000 : 0000:05:00.0
>>> 00000000-00000000 : 0000:05:00.1
>>> 00000000-00000000 : PCI Bus 0000:09
>>> 00000000-00000000 : 0000:09:00.0
>>> 00000000-00000000 : 0000:09:00.1
>>> 00000000-00000000 : 0000:00:10.0
>>> 00000000-00000000 : ahci
>>> 00000000-00000000 : 0000:00:10.1
>>> 00000000-00000000 : ahci
>>> 00000000-00000000 : PCI Bus 0000:80
>>> 00000000-00000000 : PCI Bus 0000:83
>>> 00000000-00000000 : 0000:83:00.0
>>> 00000000-00000000 : 0000:83:00.0
>>> 00000000-00000000 : nvme
>>> 00000000-00000000 : PCI Bus 0000:89
>>> 00000000-00000000 : 0000:89:00.0
>>> 00000000-00000000 : e1000e
>>> 00000000-00000000 : 0000:89:00.0
>>> 00000000-00000000 : 0000:89:00.0
>>> 00000000-00000000 : e1000e
>>> 00000000-00000000 : 0000:89:00.0
>>> 00000000-00000000 : e1000e
>>> 00000000-00000000 : PCI Bus 0000:8d
>>> 00000000-00000000 : 0000:8d:00.0
>>> 00000000-00000000 : 0000:8d:00.0
>>> 00000000-00000000 : mpt3sas
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : Kernel code
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : Kernel data
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : CAV901C:00
>>> 00000000-00000000 : CAV901D:00
>>> 00000000-00000000 : CAV901C:00
>>> 00000000-00000000 : CAV901E:00
>>> 00000000-00000000 : CAV901C:00
>>> 00000000-00000000 : CAV901F:00
>>> 00000000-00000000 : CAV901C:00
>>> 00000000-00000000 : CAV9006:00
>>> 00000000-00000000 : CAV9006:00
>>> 00000000-00000000 : ARMH0011:00
>>> 00000000-00000000 : ARMH0011:00
>>> 00000000-00000000 : arm-smmu-v3.0.auto
>>> 00000000-00000000 : arm-smmu-v3.0.auto
>>> 00000000-00000000 : arm-smmu-v3.1.auto
>>> 00000000-00000000 : arm-smmu-v3.1.auto
>>> 00000000-00000000 : arm-smmu-v3.2.auto
>>> 00000000-00000000 : arm-smmu-v3.2.auto
>>> 00000000-00000000 : CAV901C:01
>>> 00000000-00000000 : CAV901D:01
>>> 00000000-00000000 : CAV901C:01
>>> 00000000-00000000 : CAV901E:01
>>> 00000000-00000000 : CAV901C:01
>>> 00000000-00000000 : CAV901F:01
>>> 00000000-00000000 : CAV901C:01
>>> 00000000-00000000 : CAV9007:06
>>> 00000000-00000000 : CAV9007:06
>>> 00000000-00000000 : arm-smmu-v3.3.auto
>>> 00000000-00000000 : arm-smmu-v3.3.auto
>>> 00000000-00000000 : arm-smmu-v3.4.auto
>>> 00000000-00000000 : arm-smmu-v3.4.auto
>>> 00000000-00000000 : arm-smmu-v3.5.auto
>>> 00000000-00000000 : arm-smmu-v3.5.auto
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : System RAM
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : reserved
>>> 00000000-00000000 : PCI Bus 0000:00
>>> 00000000-00000000 : PCI Bus 0000:01
>>> 00000000-00000000 : 0000:01:00.0
>>> 00000000-00000000 : 0000:01:00.1
>>> 00000000-00000000 : 0000:01:00.0
>>> 00000000-00000000 : 0000:01:00.1
>>> 00000000-00000000 : 0000:01:00.0
>>> 00000000-00000000 : 0000:01:00.1
>>> 00000000-00000000 : PCI Bus 0000:05
>>> 00000000-00000000 : 0000:05:00.0
>>> 00000000-00000000 : bnx2x
>>> 00000000-00000000 : 0000:05:00.1
>>> 00000000-00000000 : bnx2x
>>> 00000000-00000000 : 0000:05:00.0
>>> 00000000-00000000 : bnx2x
>>> 00000000-00000000 : 0000:05:00.0
>>> 00000000-00000000 : bnx2x
>>> 00000000-00000000 : 0000:05:00.1
>>> 00000000-00000000 : bnx2x
>>> 00000000-00000000 : 0000:05:00.1
>>> 00000000-00000000 : bnx2x
>>> 00000000-00000000 : PCI Bus 0000:09
>>> 00000000-00000000 : 0000:09:00.0
>>> 00000000-00000000 : i40e
>>> 00000000-00000000 : 0000:09:00.1
>>> 00000000-00000000 : i40e
>>> 00000000-00000000 : 0000:09:00.0
>>> 00000000-00000000 : 0000:09:00.1
>>> 00000000-00000000 : 0000:09:00.0
>>> 00000000-00000000 : i40e
>>> 00000000-00000000 : 0000:09:00.1
>>> 00000000-00000000 : i40e
>>> 00000000-00000000 : 0000:09:00.0
>>> 00000000-00000000 : 0000:09:00.1
>>> 00000000-00000000 : 0000:00:0f.0
>>> 00000000-00000000 : xhci-hcd
>>> 00000000-00000000 : 0000:00:0f.0
>>> 00000000-00000000 : 0000:00:0f.1
>>> 00000000-00000000 : xhci-hcd
>>> 00000000-00000000 : 0000:00:0f.1
>>> 00000000-00000000 : 0000:00:10.0
>>> 00000000-00000000 : ahci
>>> 00000000-00000000 : 0000:00:10.1
>>> 00000000-00000000 : ahci
>>> 00000000-00000000 : PCI Bus 0000:80
>>>
>>
>> resending with correct logs (after login as root)
>>
>> $ cat /proc/iomem
>> 30000000-37ffffff : PCI ECAM
>> 38000000-3fffffff : PCI ECAM
>> 40000000-5fffffff : PCI Bus 0000:00
>> 40000000-417fffff : PCI Bus 0000:0f
>> 40000000-417fffff : PCI Bus 0000:10
>> 40000000-40ffffff : 0000:10:00.0
>> 41000000-4101ffff : 0000:10:00.0
>> 41800000-418fffff : PCI Bus 0000:01
>> 41800000-4183ffff : 0000:01:00.0
>> 41840000-4187ffff : 0000:01:00.1
>> 41900000-419fffff : PCI Bus 0000:05
>> 41900000-4197ffff : 0000:05:00.0
>> 41980000-419fffff : 0000:05:00.1
>> 41a00000-41afffff : PCI Bus 0000:09
>> 41a00000-41a7ffff : 0000:09:00.0
>> 41a80000-41afffff : 0000:09:00.1
>> 41b00000-41b0ffff : 0000:00:10.0
>> 41b00000-41b0ffff : ahci
>> 41b10000-41b1ffff : 0000:00:10.1
>> 41b10000-41b1ffff : ahci
>> 60000000-7fffffff : PCI Bus 0000:80
>> 60000000-600fffff : PCI Bus 0000:83
>> 60000000-6001ffff : 0000:83:00.0
>> 60020000-60023fff : 0000:83:00.0
>> 60020000-60023fff : nvme
>> 60100000-601fffff : PCI Bus 0000:89
>> 60100000-6017ffff : 0000:89:00.0
>> 60100000-6017ffff : e1000e
>> 60180000-601bffff : 0000:89:00.0
>> 601c0000-601dffff : 0000:89:00.0
>> 601c0000-601dffff : e1000e
>> 601e0000-601e3fff : 0000:89:00.0
>> 601e0000-601e3fff : e1000e
>> 60200000-603fffff : PCI Bus 0000:8d
>> 60200000-602fffff : 0000:8d:00.0
>> 60300000-6030ffff : 0000:8d:00.0
>> 60300000-6030ffff : mpt3sas
>> 802f0000-8030ffff : reserved
>> e6247000-e6247fff : reserved
>> e6720000-e690ffff : reserved
>> e6a90000-e6a9ffff : reserved
>> e6ab0000-e721ffff : reserved
>> e7240000-e7240fff : reserved
>> fac00000-fafdffff : reserved
>> 400040400-40004041f : CAV901C:00
>> 400040480-400040567 : CAV901D:00
>> 400040480-400040567 : CAV901C:00
>> 400040600-40004073b : CAV901E:00
>> 400040600-40004073b : CAV901C:00
>> 400041400-40004177f : CAV901F:00
>> 400041400-40004177f : CAV901C:00
>> 402000100-402000fff : CAV9006:00
>> 402000100-402000fff : CAV9006:00
>> 402020000-40202ffff : ARMH0011:00
>> 402020000-40202ffff : ARMH0011:00
>> 402300000-40230ffff : arm-smmu-v3.0.auto
>> 402300000-40230ffff : arm-smmu-v3.0.auto
>> 402320000-40232ffff : arm-smmu-v3.1.auto
>> 402320000-40232ffff : arm-smmu-v3.1.auto
>> 402340000-40234ffff : arm-smmu-v3.2.auto
>> 402340000-40234ffff : arm-smmu-v3.2.auto
>> 440040400-44004041f : CAV901C:01
>> 440040480-440040567 : CAV901D:01
>> 440040480-440040567 : CAV901C:01
>> 440040600-44004073b : CAV901E:01
>> 440040600-44004073b : CAV901C:01
>> 440041400-44004177f : CAV901F:01
>> 440041400-44004177f : CAV901C:01
>> 4421a0000-4421affff : CAV9007:06
>> 4421a0000-4421affff : CAV9007:06
>> 442300000-44230ffff : arm-smmu-v3.3.auto
>> 442300000-44230ffff : arm-smmu-v3.3.auto
>> 442320000-44232ffff : arm-smmu-v3.4.auto
>> 442320000-44232ffff : arm-smmu-v3.4.auto
>> 442340000-44234ffff : arm-smmu-v3.5.auto
>> 442340000-44234ffff : arm-smmu-v3.5.auto
>> b81200000-c811fffff : System RAM
>> b81280000-b8270ffff : Kernel code
>> b82710000-b82dfffff : reserved
>> b82e00000-b83168fff : Kernel data
>> b83169000-baccd7fff : reserved
>> c78a00000-c7fffffff : reserved
>> c80129000-c801a9fff : reserved
>> c801aa000-c809e9fff : reserved
>> c809ec000-c809eefff : reserved
>> c809ef000-c811fffff : reserved
>> 10000000000-13fffffffff : PCI Bus 0000:00
>> 10000000000-100013fffff : PCI Bus 0000:01
>> 10000000000-100007fffff : 0000:01:00.0
>> 10000800000-10000ffffff : 0000:01:00.1
>> 10001000000-1000101ffff : 0000:01:00.0
>> 10001020000-1000103ffff : 0000:01:00.1
>> 10001040000-1000104ffff : 0000:01:00.0
>> 10001050000-1000105ffff : 0000:01:00.1
>> 10001400000-100037fffff : PCI Bus 0000:05
>> 10001400000-1000140ffff : 0000:05:00.0
>> 10001400000-1000140ffff : bnx2x
>> 10001410000-1000141ffff : 0000:05:00.1
>> 10001410000-1000141ffff : bnx2x
>> 10001800000-10001ffffff : 0000:05:00.0
>> 10001800000-10001ffffff : bnx2x
>> 10002000000-100027fffff : 0000:05:00.0
>> 10002000000-100027fffff : bnx2x
>> 10002800000-10002ffffff : 0000:05:00.1
>> 10002800000-10002ffffff : bnx2x
>> 10003000000-100037fffff : 0000:05:00.1
>> 10003000000-100037fffff : bnx2x
>> 10003800000-100053fffff : PCI Bus 0000:09
>> 10003800000-10003ffffff : 0000:09:00.0
>> 10003800000-10003ffffff : i40e
>> 10004000000-100047fffff : 0000:09:00.1
>> 10004000000-100047fffff : i40e
>> 10004800000-10004bfffff : 0000:09:00.0
>> 10004c00000-10004ffffff : 0000:09:00.1
>> 10005000000-10005007fff : 0000:09:00.0
>> 10005000000-10005007fff : i40e
>> 10005008000-1000500ffff : 0000:09:00.1
>> 10005008000-1000500ffff : i40e
>> 10005010000-1000510ffff : 0000:09:00.0
>> 10005110000-1000520ffff : 0000:09:00.1
>> 10005400000-1000540ffff : 0000:00:0f.0
>> 10005400000-1000540ffff : xhci-hcd
>> 10005410000-1000541ffff : 0000:00:0f.0
>> 10005420000-1000542ffff : 0000:00:0f.1
>> 10005420000-1000542ffff : xhci-hcd
>> 10005430000-1000543ffff : 0000:00:0f.1
>> 10005440000-1000544ffff : 0000:00:10.0
>> 10005440000-1000544ffff : ahci
>> 10005450000-1000545ffff : 0000:00:10.1
>> 10005450000-1000545ffff : ahci
>> 14000000000-17fffffffff : PCI Bus 0000:80
>>
>>
>> failure with crashkernel=1G
>>
>> :~$ dmesg | grep crash
>> [ 0.000000] cannot allocate crashkernel (size:0x40000000)
>> [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
>> root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro nowatchdog earlycon
>> crashkernel=1G crashkernel=250M,low
>> [ 29.326916] crashkernel=250M,low
>>
>
> I read these clearly, found that your all testcases failed including
> "crashkernel=4G@0xb81200000 crashkernel=250M,low".
>
I tested 3 scenarios
1) crashkernel=4G@0xb81200000 crashkernel=250M,low : Allocation Passed
2) crashkernel=4G crashkernel=250M,low : Allocation failed
3) crashkernel=2G crashkernel=250M,low : Allocation failed
4) crashkernel=1G crashkernel=250M,low : Allocation failed
> There is no "Crash kernel (low)" in all your tests, that is there is no enough
> low memory, in these cases, parameters equal to 4G@0xb81200000, crashkernel=4G
> and crashkernel=1G.
>
> crashkernel=4G and crashkernel=1G all failed because there is no low memory.
>
As per my understanding, this patch series allow to allocate memory
above 4G range. So For crashkernel = 1G: if no memory found in low
memory range, it will automatically be allocated from above 4G range.
--pk