Messages in this thread | | | Date | Thu, 04 Mar 2004 14:02:54 -0800 | From | George Anzinger <> | Subject | Re: [Kgdb-bugreport] [PATCH] Kill kgdb_serial |
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Amit S. Kale wrote: > On Thursday 04 Mar 2004 6:04 am, George Anzinger wrote: > >>Tom Rini wrote: >> >>>On Wed, Mar 03, 2004 at 04:51:06PM +0100, Pavel Machek wrote: >>> >>>>Hi! >>>> >>>> >>>>>>>More precisely: >>>>>>>http://lkml.org/lkml/2004/2/11/224 >>>>>> >>>>>>Well, that just says Andrew does not care too much. I think that >>>>>>having both serial and ethernet support *is* good idea after all... I >>>>>>have few machines here, some of them do not have serial, and some of >>>>>>them do not have supported ethernet. It would be nice to use same >>>>>>kernel on all of them. Also distribution wants to have "debugging >>>>>>kernel", but does _not_ want to have 10 of them. >>>>> >>>>>But unless I'm missing something, supporting eth or 8250 at all times >>>>>doesn't work right now anyhow, as eth if available will always take >>>>>over. >>>> >>>>Well, that can be fixed. [Probably if kgdbeth= is not passed, ethernet >>>>interface should not take over. So user selects which one should be >>>>used by either passing kgdbeth or kgdb8250. That means that 8250 >>>>should not be initialized until user passes kgdb8250=... not sure how >>>>you'll like that]. >>> >>>At this point, I'm going to give up on killing kgdb_serial, and pass >>>along some comments from David Woodhouse on IRC as well (I was talking >>>about this issue, and the init/main.c change): >>>(Tartarus == me, dwmw2 == David Woodhouse) >>> >>><Tartarus> dwmw2, the problem is how do you deal with all of the >>>possibilities of i/o (8250, kgdboe, or other serial) and do you allow >>>for passing 'gdb' on the command line to result in kgdb not being dropped >>>into? You can always break in later on of course >>><dwmw2> parse command line early for 'gdb=' argument specifying which >>>i/o device to use. init kgdb core early. init each i/o device as early >>>as possible for that i/o device. Start the selected i/o device as soon >>>as it becomes available. >>><dwmw2> just like console could, if we looked for console= a little bit >>>earlier. (forget all the earlyconsole shite, it's not necessary) >>><dwmw2> Tartarrus, do the __early_setup() thing to replace __setup() for >>>selected args. We can use that for console= too. >>><dwmw2> since 'console=' on the command line _already_ remembers its >>>arguments, and starts to use the offending device as soon as it gets >>>registered with register_console(). >>><Tartarus> dwmw2, __early_setup() ? >>><dwmw2> See __setup("gdb=", gdb_setup_func); >>><dwmw2> Replace with __early_setup(...) >>><Tartarus> where is __early_setup ? >>><dwmw2> before we normally parse the command line >>><dwmw2> in my head >>> >>>So perhaps someone can take these ideas and fix both problems... :) >>>(I've got some other stuff I need to work on today). >> >>Well, __early_setup could mean the fist setup call and if so that would be >>what we do in -mm. It is done by putting the code in the first module ld >>sees, not nice, but it works. > > > I would prefer something that modifies start_kernel itself, rather than > depending on ld. It will split start_kernel command line parsing into early > parse and late parse, but that's the price we have to pay to do special > parsing of kgdb arguments.
There was some talk along these lines at one point, I don't think anything came of it. We would like it to be the very first, not just one of the first.
I think modifying the kernel to support this for kgdb is more like the tail wagging the dog :)
-- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml
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