Re: core dumps on signals

H. Peter Anvin (hpa@transmeta.com)
26 Feb 1999 06:33:14 GMT

Followup to: <199902260548.AAA14176@saturn.cs.uml.edu>
By author: "Albert D. Cahalan" <acahalan@cs.uml.edu>
In newsgroup: linux.dev.kernel
>
> So the library is supposed to define signal names (and forget libc 5)...
> Which signal is supposed to be SIGSYS? Neither of the two junk signals
> dump core, so they can not be substituted without kernel changes.
>
> (only 4 of 8 ports have this problem: i386, arm, m68k, ppc)
>
> Name Unix98 Linux
> ---------------------
> ABRT core core
> FPE core core
> ILL core core
> QUIT core core
> SEGV core core
> TRAP core core
> SYS core n/a (Missing! This is bad!)
> BUS core exit
> XCPU core exit
> XFSZ core exit
> ALRM exit exit
> HUP exit exit
> INT exit exit
> KILL exit exit
> PIPE exit exit
> POLL exit exit
> PROF exit exit
> TERM exit exit
> USR1 exit exit
> USR2 exit exit
> VTALRM exit exit
> PWR n/a exit (normal systems would ignore by default)

I don't think so; SIGPWR sent to init means it should shut down the
system as soon as possible. If init dies, the system gets uncleanly
shut down, but less uncleanly than a power interruption (at least the
disks are idled.) Therefore this is eminently sensible.

> STKFLT n/a exit (this is Linux-specific junk)
> UNUSED n/a exit (this is Linux-specific junk)

I would still like to suggest these two getting recycled as SIGTHREAD1
and SIGTHREAD2, for LinuxThreads to use.

> WINCH n/a ignore
> CHLD ignore ignore
> URG ignore ignore
> TSTP stop ignore if daemon, otherwise exit
> TTIN stop ignore if daemon, otherwise exit
> TTOU stop ignore if daemon, otherwise exit

This is just wrong: Linux stops if the handler is default on TSTP,
TTIN, and TTOU which is perfectly correct behaviour. If what you had
up there was true, ^Z would kill your process.

> STOP stop stop
> CONT unstop unstop
> EMT n/a n/a (normal systems would core by default)

-hpa

-- 
"Linux is a very complete and sophisticated operating system.  There
are, and will be, large numbers of applications available for it."
    -- Paul Maritz, Group Vice President for Platforms And Applications,
       Microsoft Corporation [Reference at: http://www.kernel.org/~hpa/ms.html]


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