Messages in this thread | | | Subject | Re: [PATCH v3 1/5] kernel/sysctl: support setting sysctl parameters from kernel command line | From | Vlastimil Babka <> | Date | Tue, 28 Apr 2020 10:09:37 +0200 |
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On 4/27/20 8:33 PM, Andrew Morton wrote: > On Mon, 27 Apr 2020 20:04:29 +0200 Vlastimil Babka <vbabka@suse.cz> wrote: > >> ... >> >> + sysctl.*= [KNL] >> + Set a sysctl parameter, right before loading the init >> + process, as if the value was written to the respective >> + /proc/sys/... file. Both '.' and '/' are recognized as >> + separators. Unrecognized parameters and invalid values >> + are reported in the kernel log. Sysctls registered >> + later by a loaded module cannot be set this way. >> + Example: sysctl.vm.swappiness=40 > > Why support "."? I think only supporting "/" is perfectly adequate and > simplifies documentation. It aligns the command-line syntax with the > rest of the sysctl documentation. I'm not seeing the need to provide > two ways of doing the same thing?
AFAIK the "." is traditional, and "/" is a newer artefact of moving from the binary syscall form to procfs based form. So by "command-line syntax" you mean echo and cat, not sysctl tool? Because "man sysctl" says:
variable The name of a key to read from. An example is kernel.ostype. The '/' separator is also accepted in place of a '.'.
So I'm not strongly against supporting only / but I expect most people are used to the . and it will take them two attempts to pass the sysctl boot parameter correctly if they don't use it regularly - first trying . form, wonder why it doesn't work, then read the doc and realize it's not supported?
Vlastimil
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