Subject: Re: no buffer space available
To: NetBSD User's Discussion List <firstname.lastname@example.org>
From: Steven M. Bellovin <email@example.com>
Date: 06/24/2001 21:28:42
In message <20010625012109.559511A5@proven.weird.com>, Greg A. Woods writes:
>[ On Sunday, June 24, 2001 at 19:17:13 (-0400), Steven M. Bellovin wrote: ]
>> Subject: Re: no buffer space available
>> You can get ENOBUFS when the output queue for the device is full, I
>> believe. Note the following code fragment from if_ppp.c:
>That might explain why I didn't ever get any similar behaviour when I
>was running PPP, because that was on BSD/OS 1.1.
>But I don't think it can explain how an ethernet-only router like mine
>can get clogged....
A lost interrupt could probably produce the same symptoms, if the
driver doesn't have adequate recovery code, such as a watchdog timer.
I haven't looked at any of the NetBSD Ethernet drivers to see what they
do. But I remember the first time I saw a device driver that could
handle such situations -- it was amazing how much of a difference it
made to system stability. (Anyone else remember having to pop out
the unit number plug on IBM 2314 disk drives, or do a 'vary ...,offline'/
'vary ...,online' sequence on IBM mainframes to recover from lost disk
--Steve Bellovin, http://www.research.att.com/~smb