Messages in this thread | | | Subject | Re: [PATCH v2] init: Print out unknown kernel parameters | From | Randy Dunlap <> | Date | Thu, 13 May 2021 09:06:35 -0700 |
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On 5/13/21 6:00 AM, Andrew Halaney wrote: > On Wed, May 12, 2021 at 04:00:21PM -0700, Randy Dunlap wrote: >> On 5/11/21 2:10 PM, Andrew Halaney wrote: >>> It is easy to foobar setting a kernel parameter on the command line >>> without realizing it, there's not much output that you can use to >>> assess what the kernel did with that parameter by default. >>> >>> Make it a little more explicit which parameters on the command line >>> _looked_ like a valid parameter for the kernel, but did not match >>> anything and ultimately got tossed to init. This is very similar to the >>> unknown parameter message received when loading a module. >>> >>> This assumes the parameters are processed in a normal fashion, some >>> parameters (dyndbg= for example) don't register their >>> parameter with the rest of the kernel's parameters, and therefore >>> always show up in this list (and are also given to init - like the >>> rest of this list). >>> >>> Another example is BOOT_IMAGE= is highlighted as an offender, which it >>> technically is, but is passed by LILO and GRUB so most systems will see >>> that complaint. >>> >>> An example output where "foobared" and "unrecognized" are intentionally >>> invalid parameters: >>> >>> Kernel command line: BOOT_IMAGE=/boot/vmlinuz-5.12-dirty debug log_buf_len=4M foobared unrecognized=foo >>> Unknown command line parameters: foobared BOOT_IMAGE=/boot/vmlinuz-5.12-dirty unrecognized=foo >> >> Hi Andrew, >> What order is the list of unknown command line parameters listed in? > > Hi Randy, > > That's a good question considering that they are out of order in my > example output compared to the command line. The order is parameters > without an "=val", then those with an "=val", and within those groups > they should be ordered as they are on the command line. > > This is because I'm using the processing work done by > unknown_bootoption(), which stores them in two separate lists to pass to > init later (for arguments and environment). I am "stealing" from those > here: > > for (p = &argv_init[1]; *p; p++) > end += sprintf(end, " %s", *p); > for (p = &envp_init[2]; *p; p++) > end += sprintf(end, " %s", *p); > > hence the differing output order from the command line. I didn't > see much value in trying to duplicate that processing logic to get them in > a single list in the order of the command line itself. I debated looking > at the command line and searching each of the offending lists for that > entry to get them in the order of the command line but decided to keep > it simple here since it was achieving what I wanted.
Thanks for explaining. That's what I was looking for.
-- ~Randy
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