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SubjectRe: [PATCH] kconfig: remove EXPERT from CHECKPOINT_RESTORE
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On 07/12/2018 07:33 PM, Eric W. Biederman wrote:
>
> Adrian Reber <adrian@lisas.de> writes:
>
>> The CHECKPOINT_RESTORE configuration option was introduced in 2012 and
>> combined with EXPERT. CHECKPOINT_RESTORE is already enabled in many
>> distribution kernels and also part of the defconfigs of various
>> architectures.
>>
>> To make it easier for distributions to enable CHECKPOINT_RESTORE this
>> removes EXPERT and moves the configuration option out of the EXPERT
>> block.
>
> I think we should change the help text at the same time, to match
> our improve understanding of the situation.
>
> Does anyone remember why this option was added at all?

Sure! Quoting Andrew's ~7 years ago akpm branch merge e-mail:

However I'm less confident than the developers that it will all
eventually work! So what I'm asking them to do is to wrap each piece
of new code inside CONFIG_CHECKPOINT_RESTORE. So if it all
eventually comes to tears and the project as a whole fails, it should
be a simple matter to go through and delete all trace of it.

the best link with full e-mail I googled for is
https://gitlab.imag.fr/kaunetem/linux-kaunetem/commit/099469502f62fbe0d7e4f0b83a2f22538367f734

-- Pavel

> Why this option was placed under expert?
>
> What is the value of disabling this functionality ever?
>
> Is there any reason why we don't just delete CONFIG_CHECKPOINT_RESTORE
> entirely?
>
> Certainly we are at a point where distro's are enabling this so hiding
> it behind CONFIG_EXPERT with a default of N seems inapparopriate.
>
> The only thing I can imagine might be sensible is changing the default
> to Y and leaving it behind CONFIG_EXPERT.
>
> I want to know what is the point of maintaining all of the complexity of
> the ifdefs. If no one can come up with a reason I say let's just remove
> CONFIG_CHECKPOINT_RESTORE entirely.
>
> Eric
>
>
>> Signed-off-by: Adrian Reber <adrian@lisas.de>
>> Cc: Oleg Nesterov <oleg@redhat.com>
>> Cc: Pavel Emelyanov <xemul@virtuozzo.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Eric W. Biederman <ebiederm@xmission.com>
>> Cc: Andrei Vagin <avagin@virtuozzo.com>
>> Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
>> ---
>> init/Kconfig | 24 ++++++++++++------------
>> 1 file changed, 12 insertions(+), 12 deletions(-)
>>
>> diff --git a/init/Kconfig b/init/Kconfig
>> index 041f3a022122..9c529c763326 100644
>> --- a/init/Kconfig
>> +++ b/init/Kconfig
>> @@ -932,6 +932,18 @@ config NET_NS
>>
>> endif # NAMESPACES
>>
>> +config CHECKPOINT_RESTORE
>> + bool "Checkpoint/restore support"
>> + select PROC_CHILDREN
>> + default n
>> + help
>> + Enables additional kernel features in a sake of checkpoint/restore.
>> + In particular it adds auxiliary prctl codes to setup process text,
>> + data and heap segment sizes, and a few additional /proc filesystem
>> + entries.
>> +
>> + If unsure, say N here.
>> +
>> config SCHED_AUTOGROUP
>> bool "Automatic process group scheduling"
>> select CGROUPS
>> @@ -1348,18 +1360,6 @@ config MEMBARRIER
>>
>> If unsure, say Y.
>>
>> -config CHECKPOINT_RESTORE
>> - bool "Checkpoint/restore support" if EXPERT
>> - select PROC_CHILDREN
>> - default n
>> - help
>> - Enables additional kernel features in a sake of checkpoint/restore.
>> - In particular it adds auxiliary prctl codes to setup process text,
>> - data and heap segment sizes, and a few additional /proc filesystem
>> - entries.
>> -
>> - If unsure, say N here.
>> -
>> config KALLSYMS
>> bool "Load all symbols for debugging/ksymoops" if EXPERT
>> default y
> .
>

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