by chenzhou

[permalink] [raw]

Subject: Re: [PATCH v14 09/11] x86, arm64: Add ARCH_WANT_RESERVE_CRASH_KERNEL config

On 2021/2/18 16:35, Baoquan He wrote:
> On 01/30/21 at 03:10pm, Chen Zhou wrote:
>> We make the functions reserve_crashkernel[_low]() as generic for
>> x86 and arm64. Since reserve_crashkernel[_low]() implementations
>> are quite similar on other architectures as well, we can have more
>> users of this later.
>>
>> So have CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL in arch/Kconfig and
>> select this by X86 and ARM64.
> This looks much better with the help of
> CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL. And please take off the
> 'Suggested-by' tag from me, I just don't like the old CONFIG_X86 and
> CONFIG_ARM64 ifdeffery way in v13, Mike suggested this ARCH_WANT_
> option.
OK, i will delete this.
>
> And the two dummy function reserve_crashkernel() in x86 and arm64 looks
> not so good, but I don't have better idea. Maybe add
> CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL iddeffery in the call site of
> reserve_crashkernel() in each ARCH? Or just leave with it for now if no
> other people has concern or suggestion about it.
>
> Anyway, ack this one.
>
> Acked-by: Baoquan He <[email protected]>
>
> Thanks
> Baoquan
>
>
>> Suggested-by: Mike Rapoport <[email protected]>
>> Suggested-by: Baoquan He <[email protected]>
>> Signed-off-by: Chen Zhou <[email protected]>
>> ---
>> arch/Kconfig | 3 +++
>> arch/arm64/Kconfig | 1 +
>> arch/x86/Kconfig | 2 ++
>> kernel/crash_core.c | 7 ++-----
>> 4 files changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/Kconfig b/arch/Kconfig
>> index 24862d15f3a3..0ca1ff5bb157 100644
>> --- a/arch/Kconfig
>> +++ b/arch/Kconfig
>> @@ -24,6 +24,9 @@ config KEXEC_ELF
>> config HAVE_IMA_KEXEC
>> bool
>>
>> +config ARCH_WANT_RESERVE_CRASH_KERNEL
>> + bool
>> +
>> config SET_FS
>> bool
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index f39568b28ec1..09365c7ff469 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -82,6 +82,7 @@ config ARM64
>> select ARCH_WANT_FRAME_POINTERS
>> select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)
>> select ARCH_WANT_LD_ORPHAN_WARN
>> + select ARCH_WANT_RESERVE_CRASH_KERNEL if KEXEC_CORE
>> select ARCH_HAS_UBSAN_SANITIZE_ALL
>> select ARM_AMBA
>> select ARM_ARCH_TIMER
>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>> index 21f851179ff0..e6926fcb4a40 100644
>> --- a/arch/x86/Kconfig
>> +++ b/arch/x86/Kconfig
>> @@ -12,6 +12,7 @@ config X86_32
>> depends on !64BIT
>> # Options that are inherently 32-bit kernel only:
>> select ARCH_WANT_IPC_PARSE_VERSION
>> + select ARCH_WANT_RESERVE_CRASH_KERNEL if KEXEC_CORE
>> select CLKSRC_I8253
>> select CLONE_BACKWARDS
>> select GENERIC_VDSO_32
>> @@ -28,6 +29,7 @@ config X86_64
>> select ARCH_HAS_GIGANTIC_PAGE
>> select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
>> select ARCH_USE_CMPXCHG_LOCKREF
>> + select ARCH_WANT_RESERVE_CRASH_KERNEL if KEXEC_CORE
>> select HAVE_ARCH_SOFT_DIRTY
>> select MODULES_USE_ELF_RELA
>> select NEED_DMA_MAP_STATE
>> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
>> index 8479be270c0b..2c5783985db5 100644
>> --- a/kernel/crash_core.c
>> +++ b/kernel/crash_core.c
>> @@ -320,9 +320,7 @@ int __init parse_crashkernel_low(char *cmdline,
>> * --------- Crashkernel reservation ------------------------------
>> */
>>
>> -#ifdef CONFIG_KEXEC_CORE
>> -
>> -#if defined(CONFIG_X86) || defined(CONFIG_ARM64)
>> +#ifdef CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL
>> static int __init reserve_crashkernel_low(void)
>> {
>> #ifdef CONFIG_64BIT
>> @@ -450,8 +448,7 @@ void __init reserve_crashkernel(void)
>> crashk_res.start = crash_base;
>> crashk_res.end = crash_base + crash_size - 1;
>> }
>> -#endif
>> -#endif /* CONFIG_KEXEC_CORE */
>> +#endif /* CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL */
>>
>> Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>> void *data, size_t data_len)
>> --
>> 2.20.1
>>
> .
>

2021-02-20 03:28:36

by chenzhou

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Subject: Re: [PATCH v14 11/11] kdump: update Documentation about crashkernel

On 2021/2/18 16:40, Baoquan He wrote:
> On 01/30/21 at 03:10pm, Chen Zhou wrote:
>> For arm64, the behavior of crashkernel=X has been changed, which
>> tries low allocation in DMA zone and fall back to high allocation
>> if it fails.
>>
>> We can also use "crashkernel=X,high" to select a high region above
>> DMA zone, which also tries to allocate at least 256M low memory in
>> DMA zone automatically and "crashkernel=Y,low" can be used to allocate
>> specified size low memory.
>>
>> So update the Documentation.
> Nice document adding which also takes care of x86 code implementation,
> thanks. By the way, maybe you can remove John's 'Tested-by' since it
> doesn't make much sense to test a document patch.
I will remove the Tested-by in next version.
>
> Acked-by: Baoquan He <[email protected]>
>
>> Signed-off-by: Chen Zhou <[email protected]>
>> Tested-by: John Donnelly <[email protected]>
>> ---
>> Documentation/admin-guide/kdump/kdump.rst | 22 ++++++++++++++++---
>> .../admin-guide/kernel-parameters.txt | 11 ++++++++--
>> 2 files changed, 28 insertions(+), 5 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
>> index 75a9dd98e76e..0877c76f8015 100644
>> --- a/Documentation/admin-guide/kdump/kdump.rst
>> +++ b/Documentation/admin-guide/kdump/kdump.rst
>> @@ -299,7 +299,16 @@ Boot into System Kernel
>> "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>> starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>>
>> - On x86 and x86_64, use "crashkernel=64M@16M".
>> + On x86 use "crashkernel=64M@16M".
>> +
>> + On x86_64, use "crashkernel=X" to select a region under 4G first, and
>> + fall back to reserve region above 4G. And go for high allocation
>> + directly if the required size is too large.
>> + We can also use "crashkernel=X,high" to select a region above 4G, which
>> + also tries to allocate at least 256M below 4G automatically and
>> + "crashkernel=Y,low" can be used to allocate specified size low memory.
>> + Use "crashkernel=Y@X" if you really have to reserve memory from specified
>> + start address X.
>>
>> On ppc64, use "crashkernel=128M@32M".
>>
>> @@ -316,8 +325,15 @@ Boot into System Kernel
>> kernel will automatically locate the crash kernel image within the
>> first 512MB of RAM if X is not given.
>>
>> - On arm64, use "crashkernel=Y[@X]". Note that the start address of
>> - the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
>> + On arm64, use "crashkernel=X" to try low allocation in DMA zone and
>> + fall back to high allocation if it fails.
>> + We can also use "crashkernel=X,high" to select a high region above
>> + DMA zone, which also tries to allocate at least 256M low memory in
>> + DMA zone automatically.
>> + "crashkernel=Y,low" can be used to allocate specified size low memory.
>> + Use "crashkernel=Y@X" if you really have to reserve memory from
>> + specified start address X. Note that the start address of the kernel,
>> + X if explicitly specified, must be aligned to 2MiB (0x200000).
>>
>> Load the Dump-capture Kernel
>> ============================
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index a10b545c2070..908e5c8b61ba 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -738,6 +738,9 @@
>> [KNL, X86-64] Select a region under 4G first, and
>> fall back to reserve region above 4G when '@offset'
>> hasn't been specified.
>> + [KNL, arm64] Try low allocation in DMA zone and fall back
>> + to high allocation if it fails when '@offset' hasn't been
>> + specified.
>> See Documentation/admin-guide/kdump/kdump.rst for further details.
>>
>> crashkernel=range1:size1[,range2:size2,...][@offset]
>> @@ -754,6 +757,8 @@
>> Otherwise memory region will be allocated below 4G, if
>> available.
>> It will be ignored if crashkernel=X is specified.
>> + [KNL, arm64] range in high memory.
>> + Allow kernel to allocate physical memory region from top.
>> crashkernel=size[KMG],low
>> [KNL, X86-64] range under 4G. When crashkernel=X,high
>> is passed, kernel could allocate physical memory region
>> @@ -762,13 +767,15 @@
>> 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
>> - at least 256M below 4G automatically.
>> + least 256M below 4G automatically.
>> This one let user to 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 let user to specify a low range in DMA zone for
>> + crash dump kernel.
>> cryptomgr.notests
>> [KNL] Disable crypto self-tests
>>
>> --
>> 2.20.1
>>
> .
>