Messages in this thread |  | | | Subject | Re: [PATCH] x86 built-in command line | | From | Thomas Gleixner <> | | Date | Mon, 12 Jun 2006 23:19:12 +0200 |
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On Mon, 2006-06-12 at 15:49 -0500, Matt Mackall wrote: > I don't think that's a show-stopper. I'll provide one after we decide > how this should work. > > > b. This patch will override a user-provided command line if one > > exists. This is the wrong behaviour; instead, the builtin command > > line should only apply if no user-specified command line is present. > > There are four possible behaviors: > > a) internal supercedes external (what's in the patch) > b) external supercedes internal (what you proposed) > c) external is appended to internal (what Tim proposed) > d) internal is appended to external (not very interesting) > > And there are some possible uses: > > 1) bootloader doesn't support command line > 2) bootloader has hardcoded or otherwise difficult-to-change command line > 3) automated testing for tftp boot, etc. > 4) bypassing boot protocol command line length (not yet supported) > 5) setting defaults like ACPI off, etc. > > (a) works for 1, 2, 3, and 4. > (b) works for 1, 3, and 4, provided you clear the command line in your > boot loader > (c) works for 1, 3, and 4, provided you're not trying to override > earlier arguments > > (5) generally is unworkable because our parser doesn't generally do the > right thing for options like "acpi=on acpi=off" (though it might work > in the specific case of acpi, haven't checked). If, for instance, you > try to override console, you'll get two consoles. > > So I think (a) is the way to go. If there's a use case for (b) that's > important, it's not jumping out at me. Finally, at least the arch I > inspected when preparing this patch had gone with (a) too. > > (As an example of (2), the last x86 bootloader I dealt with was written > in Forth, and getting a fresh build of it meant getting some cycles > from the last two Forth hackers on the planet.)
Well most of the bootloaders I'm working with let me change the commandline. So why must I recompile the kernel to change the console from VGA to serial ? Having a default commandline built in is great, when
- your bootloader is not able to provide one - as a default fallback if the operator(me) was too lazy to setup the bootloader
tglx
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