On Wed, Nov 04, 2020 at 11:40:09PM -0600, Tyler Hicks wrote: > On 2020-11-04 12:08:12, Will Deacon wrote: > > On Tue, Nov 03, 2020 at 09:59:52AM -0600, Tyler Hicks wrote: > > > On 2020-09-21 14:15:55, Tyler Hicks wrote: > > > > Provide the CONFIG_CMDLINE_EXTEND config option for arm64 kernels. This > > > > config option can be used to extend the kernel command line parameters, > > > > specified by the bootloader, with additional command line parameters > > > > specified in the kernel configuration. > > > > > > Hi Catalin and Will - Friendly ping on this series now that we're > > > on the other side of the 5.10 merge window. I hope it can be considered > > > for 5.10+1. Let me know if I need to rebase/resubmit. Thanks! > > > > Can you use bootconfig to achieve what you need? > > Thanks for mentioning bootconfig. I hadn't considered it. > > After reading the docs and code, I see a few reasons why I can't use it > out of the box: > > 1) It requires "bootconfig" to be appended to the kernel command line. > My proposed patch series makes it possible to append new options to > the kernel command line in situations where the bootloader is not > interactive. This presents a circular dependency problem for my use > case. > > A new config option could be added to force the enablement of > bootconfig but that would sort of be a single-use duplicate of > CONFIG_CMDLINE_EXTEND's functionality. > > 2) Not all kernel command line options can be configured using > bootconfig. For example, the "nokaslr" and "crashkernel=" parameters > are parsed/handled before setup_boot_config() is called. KASLR can > be disabled via a kernel config change but there's no config option > equivalent for "crashkernel=". Changing the "crashkernel=" command > line option is something that I need to support because a > development/debug kernel build often requires a larger reservation > and we find ourselves adjusting the "crashkernel=" value fairly > often. > > 3) External FIT image build systems do not yet support bootconfig since > it is so new. It is completely fair if you file this away in your > not-my-problem folder but simple kernel config modifications, as > needed for CONFIG_CMDLINE_EXTEND, are something that every image > build system is likely to support today. > > All that said, I do really like the look of bootconfig. Unfortunately, > it doesn't let me achieve everything I need.
Ok, well thanks for having a look. A follow-up question I have is how is this handled on x86? They don't appear to have CONFIG_CMDLINE_EXTEND either afaict. Is it because their bootloader story tends to be more uniform? Will