linux-kernel - Re: [PATCH v3 11/13] riscv/kexec: refactor for kernel/Kconfig.kexec

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Date:   Wed, 28 Jun 2023 08:30:42 -0500
From:   Eric DeVolder <eric.devolder@...cle.com>
To:     Conor Dooley <conor.dooley@...rochip.com>
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Subject: Re: [PATCH v3 11/13] riscv/kexec: refactor for kernel/Kconfig.kexec



On 6/28/23 03:20, Conor Dooley wrote:
> Hey Eric,
> 
> On Mon, Jun 26, 2023 at 12:13:30PM -0400, Eric DeVolder wrote:
>> The kexec and crash kernel options are provided in the common
>> kernel/Kconfig.kexec. Utilize the common options and provide
>> the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
> 
>> equivalent set of KEXEC and CRASH options.
> 
> I find this diff a little hard to follow (since the other half off the
> change is in another patch), so it may be me missing something, but are
> you sure?
> 
>>
>> Signed-off-by: Eric DeVolder <eric.devolder@...cle.com>
>> ---
>>   arch/riscv/Kconfig | 48 ++++++++++++++--------------------------------
>>   1 file changed, 14 insertions(+), 34 deletions(-)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 5966ad97c30c..c484abd9bbfd 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -585,48 +585,28 @@ config RISCV_BOOT_SPINWAIT
>>   
>>   	  If unsure what to do here, say N.
>>   
>> -config KEXEC
>> -	bool "Kexec system call"
>> -	depends on MMU
>> +config ARCH_SUPPORTS_KEXEC
>> +	def_bool MMU
>> +
>> +config ARCH_SELECTS_KEXEC
>> +	def_bool y
>> +	depends on KEXEC
>>   	select HOTPLUG_CPU if SMP
>> -	select KEXEC_CORE
>> -	help
>> -	  kexec is a system call that implements the ability to shutdown your
>> -	  current kernel, and to start another kernel. It is like a reboot
>> -	  but it is independent of the system firmware. And like a reboot
>> -	  you can start any kernel with it, not just Linux.
>>   
>> -	  The name comes from the similarity to the exec system call.
>> +config ARCH_SUPPORTS_KEXEC_FILE
>> +	def_bool 64BIT && MMU && CRYPTO=y && CRYPTO_SHA256=y
> 
> This looks like a change to me. Previously, only KEXEC_PURGATORY
> required these crypto options to be like so, but now KEXEC_FILE needs
> them too.
> 
> What am I missing?
Conor,
Thanks for looking at this! Indeed I erroneously applied the CRYPTO=y && CRYPTO_SHA256=y
to KEXEC_FILE rather than PURGATORY. I will correct for v4!
Thanks!
eric

> 
> Cheers,
> Conor.
> 
>>   
>> -config KEXEC_FILE
>> -	bool "kexec file based systmem call"
>> -	depends on 64BIT && MMU
>> -	select HAVE_IMA_KEXEC if IMA
>> -	select KEXEC_CORE
>> +config ARCH_SELECTS_KEXEC_FILE
>> +	def_bool y
>> +	depends on KEXEC_FILE
>>   	select KEXEC_ELF
>> -	help
>> -	  This is new version of kexec system call. This system call is
>> -	  file based and takes file descriptors as system call argument
>> -	  for kernel and initramfs as opposed to list of segments as
>> -	  accepted by previous system call.
>> -
>> -	  If you don't know what to do here, say Y.
>> +	select HAVE_IMA_KEXEC if IMA
>>   
>>   config ARCH_HAS_KEXEC_PURGATORY
>>   	def_bool KEXEC_FILE
>> -	depends on CRYPTO=y
>> -	depends on CRYPTO_SHA256=y
>>   
>> -config CRASH_DUMP
>> -	bool "Build kdump crash kernel"
>> -	help
>> -	  Generate crash dump after being started by kexec. This should
>> -	  be normally only set in special crash dump kernels which are
>> -	  loaded in the main kernel with kexec-tools into a specially
>> -	  reserved region and then later executed after a crash by
>> -	  kdump/kexec.
>> -
>> -	  For more details see Documentation/admin-guide/kdump/kdump.rst
>> +config ARCH_SUPPORTS_CRASH_DUMP
>> +	def_bool y
>>   
>>   config COMPAT
>>   	bool "Kernel support for 32-bit U-mode"
>> -- 
>> 2.31.1
>>