Date: Mon, 5 Jan 2004 16:50:13 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Bruce M Simpson <bms@spc.org> Cc: nate@root.org Subject: Re: Serial console only works after reboot? Message-ID: <20040105162219.A3687@gamplex.bde.org> In-Reply-To: <20040105003803.GB59922@saboteur.dek.spc.org> References: <20040103233044.N17367@root.org> <20040104.003330.54786488.imp@bsdimp.com> <20040104.164103.03383403.imp@bsdimp.com> <20040105003803.GB59922@saboteur.dek.spc.org>
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On Mon, 5 Jan 2004, Bruce M Simpson wrote: > On Sun, Jan 04, 2004 at 04:41:03PM -0700, M. Warner Losh wrote: > > Somewhere along the way, it gets set to 115200. Maybe it is > > initialized to 115200 by the boot blocks? I think once there's a > > divisor programmed into the serial port, the kernel console code > > doesn't change it. I could be wrong about this, however.... sio always uses the current divisor iff: - the kernel was booted with RB_SERIAL, and - the current divisor is nonzero. A divisor of 0 "can't happen", but is most likely after a cold boot when everything neglects to set the divisor (since the contents of the divisor registers is undefined after 8250-16x50 reset). However, anything that sets RB_SERIAL should set the divisor. sio cannot check that the port that it reads the divisor on is the same one that the boot program set RB_SERIAL on. > Try installing boot0sio as your boot manager. It specifically requests 9600 > 8-N-1 via BIOS calls. However this does mean that boot selection has to > happen over COM1. It should use BOOT_COMCONSOLE_PORT and BOOT_CONSOLE_SPEED like boot2 does. These are standard -- see make.conf(5). boot2 doesn't use the BIOS, so BOOT_COMCONSOLE_PORT can be a port not understood by the BIOS. boot0sio would have problems with this, and mapping BOOT_COMCONSOLE_PORT to a BIOS port number might take more code than fits. boot2 also supports setting the character format (B2SIOFMT macro), but this is nonstandard and not supported by the sio console. Brucehome | help
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