Date: Fri, 18 Apr 1997 04:22:51 +1000 From: Bruce Evans <bde@zeta.org.au> To: cshenton@it.hq.nasa.gov, hackers@FreeBSD.ORG Subject: Re: 2.2.1-R crash with looped serial gettys Message-ID: <199704171822.EAA09021@godzilla.zeta.org.au>
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>I've built a little box for pppd/mpd and routing out of a 486sx33 and >a whopping 8MB RAM; seems to mostly run fine with 2.2.1-RELEASE. It's >a fairly minimal install (Kernel User option I think) and I rebuilt >the kernel to fit the hardware. I've added a dual 16550A serial port >card to which I'll connect a pair of modems. I have getty running on >the ports, cuaa1 and cuaa2. > >PROBLEM: > >If I connect a null-modem cable between the ports, the system crashes >within a couple seconds. It's repeatable. > >It leaves no message in /var/log/messages, or dmesg, and there's no >core file. > >I presume looping the serial gettys is causing them to scream at each >other "Login:"; "Invalid Login:"; no *you* login; dammit, `login' is >not a valid login... and consumes too many resources. 4 problems: 1. Yes there is a getty war (actually probably a login war) that consumes too many resources (at 115200 bps, about 100% of a 486/33 for echoing and receiving echoes alone according to my estimates. On a 486SX/33 it is unlikely that the system runs any cycles in user mode once the war starts. 57600 bps might work). 2. There is a timeout leak in siopoll(). Oops. This causes a panic instead of a hang. With this fixed, the hang is fixable by unplugging the cable. 3. You should have seen a panic message about (2). 4. This problem should have been reported to freebsd-bugs :-). Bruce
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