On Tue, Jan 17, 2017 at 04:26:48 +1100, Nathanial Sloss wrote: > On Mon, 16 Jan 2017 00:44:02 Valery Ushakov wrote: > > On Sun, Jan 15, 2017 at 13:30:15 +0100, Martin Husemann wrote: > > > On Sun, Jan 15, 2017 at 01:59:06PM +1100, Nathanial Sloss wrote: > > > > Mapping KS_Cmd_Debugger would also work but I'm unsure as to how > > > > to do this without using wskbd key sequences in the magic. > > > > > > I don't understand - if you just assing KS_Cmd_Debugger somewhere, > > > why would you need cnmagic? > > > > Exactly. You need cnmagic(9) for detecting debugger _sequence_ > > in-band like in serial console. > > > > Your patch doesn't provide any documentation or an accompaning > > description, so I'm not sure what exactly it does, e.g. what should > > cnmagic value look like for wskbd? > > I've put an example in the updated man page for both a wskbd command > and regular text.
| +sysctl variable must be prefixed by \\001 for normal characters and/or | +control codes. | +Alternatively it can be prefixed by \\002 for wskbd commands. [...] | +The default cnmagic is \\002\\040\\0364 which on most platforms is | +<Ctrl>-<Alt>-<Esc> | +the wskbd command for | +.Xr ddb 4 . - How does \040\0364 (0x20 0xf4) correspond to <Ctrl><Alt><Esc>? - Does the fact that KS_Cmd_Debugger is defined as 0xf420 have anything to do with it? - If so, why the byte order is little endian? - KS_Cmd_Debugger becomes a meaningless placeholder - you will have it mapped by default but you can set cnmagic to something else > > But in general it's not even > > entirely clear to me what a semantic of cnmagic(9) for wskbd could be. > > Should it use individual key-presseses as the basic input stream it > > parses? If yes, you will lose the ability to use, e.g., *both* > > C-A-Esc and A-C-Esc _chords_ to break into debuger, because with > > wskbd(4) keyboard mapping they are the same _chords_, but with > > cnmagic(9) they are different _sequences_. > > That's why I have two different prefixes one for wskbd commands and > another for regular text. - What if one wants to use a mixture of them? - What happens if you specify in cnmaigc the sequence of individual keys that map (at wskbd level) to a KS_Cmd_*? > > I'd also say that the very fact that the patch doesn't use > > cn_check_magic(9) indicates in some sense that it probably does not > > implement "cnmagic support for wscons". :) > > Please see: > > ftp://ftp.netbsd.org/pub/NetBSD/misc/nat/cnmagic.v2.diff > > It now uses cn_check magic instead of the custom ws_check_magic which was > based on cn_check_magic. I still intensly dislike the very idea behind this patch. I don't think it's meaningful or useful to bolt cnmagic onto wskbd. Yes, I can theoretically imagine the possibility that someone somewhere might need a wskbd sequence to break into the debugger that for some reason cannot be expressed with just mapping KS_Cmd_Debugger. I'd estimate the probablity of that be to just slighly more than that someone somewhere will find it useful to be able to express morse code support in wskbd mappings :). You PR states the motivation as: | wscons does not support cn_magic - setting hw.cnmagic has no effect. So just drop hw.cnmagic sysctl node if the console doesn't support it. -uwe
