[PATCH v3 1/2] powerpc/fadump: reduce memory consumption for capture kernel

[Michal Suchánek]

Hello,

On Wed, 26 Apr 2017 13:05:20 +0530
Hari Bathini <hbathini at linux.vnet.ibm.com> wrote:

> With fadump (dump capture) kernel booting like a regular kernel, it
> almost needs the same amount of memory to boot as the production
> kernel, which is unwarranted for a dump capture kernel. But with no
> option to disable some of the unnecessary subsystems in fadump
> kernel, that much memory is wasted on fadump, depriving the
> production kernel of that memory.
> 
> Introduce kernel parameter 'fadump_append=' that would take regular
> kernel parameters as a comma separated list, to be enforced when
> fadump is active. This 'fadump_append=' parameter can be leveraged to
> pass parameters like nr_cpus=1, cgroup_disable=memory and numa=off,
> to disable unwarranted resources/subsystems.

According to Linux admin guide at
Documentation/admin-guide/kernel-parameters.{rst,txt}

there are arguments like isolcpus=1,2,10-20,100-2000:2/25
baycom_ser_hdx=<io>,<irq>,<mode> or console=ttyUSB0[,options] that
include a comma. On the other hand, same guide suggests that parameters
can be quoted param="spaces in here". 

So I think it would be more sensible to document the existing quoting
mechanism in the fadump_append option documentation rather than
inventing your own that is incompatible with some existing options.

Thanks

Michal