src-test/sys/ddb, branch stable/7

MFC r218825. [The implementation change to kdb_sysctl_available()

2011-03-25T18:16:49Z

cannot be MFC'd as it requires a non-MFCable change (adding drains to sbuf)]. Modify kdb_trap() so that it re-calls the dbbe_trap function as long as the debugger back-end has changed. This means that switching from ddb to gdb no longer requires a "step" which can be dangerous on an already-crashed kernel. Also add a capability to get from the gdb back-end back to ddb, by typing ^C in the console window. While here, simplify kdb_sysctl_available() by using sbuf_new_for_sysctl(), and use strlcpy() instead of strncpy() since the strlcpy semantic is desired.

Merge db_capture.c:1.6 (178492) from head to stable/7:

2008-07-01T12:15:55Z

Rename debug.ddb.capture.bytes sysctl to debug.ddb.capture.bufoff in order to match the internal variable name. Add a new sysctl debug.ddb.capture.inprogress to export the inprogress variable.

MFC: enable dynamic addition of "show all" commands

2008-04-25T16:50:48Z

Merge db_examine.c:1.35 from HEAD to RELENG_7:

2008-04-01T11:48:25Z

Add a /S mode to DDB "ex" command, which interprets and prints the value at the requested address as a symbol. For example, "ex /S aio_swake" prints the name of the function currently registered in via aio_swake hook. The change as committed differs slightly from the patch in the PR, as I force the size of the retrieved value (and the automatic address increment) to be sizeof(void *). This seems to provide the most useful auto-increment behavior, and defaults using the default size (4), which is not sizeof(void *) on 64-bit platforms. PR: 57976 Submitted by: Dan Strick

Merge db_textdump.c:1.3 from HEAD to RELENG_7:

2008-04-01T11:39:04Z

Use dump_write() instead of direct calls to di->dumper() in textdumps. Textdumps already do pretty much the same sanity checking, but abstractions and seatbelts are both useful.

Merge db_capture.c:1.5 from HEAD to RELENG_7:

2008-04-01T11:31:18Z

Increase maximum DDB capture buffer size to 5MB. PR: 119993 Suggested by: Scot Hetzel

Merge options:1.616, db_capture.c:1.4 from HEAD to RELNEG_7:

2008-04-01T11:23:32Z

Allow DDB_CAPTURE_DEFAULTBUFSIZE and DDB_CAPTURE_MAXBUFSIZE to be overridden at compile-time using kernel options of the same names. Rather than doing a compile-time CTASSERT of buffer sizes being even multiples of block sizes, just adjust them at boottime, as the failure mode is more user-friendly. MFC after: 2 months PR: 119993 Suggested by: Scot Hetzel

Merge db_capture.c:1.3 from HEAD to RELENG_7:

2008-03-31T22:09:00Z

Rename DB_ constants in db_capture.c to DDB_ so that when they are exposed as kernel compile options, they have more meaningful names. PR: 119993 MFC after: 2 months Suggested by: Scot Hetzel

Merge db_textdump.c:1.2 from HEAD to RELENG_7:

2008-03-31T22:05:09Z

Refine textdump comments slightly.

Merge files:1.1260, db_capture.c:1.2, db_command.c:1.76,

2008-03-31T21:57:24Z

db_textdump.c:1.1, ddb.h:1.46, kern_shutdown.c:1.187 from HEAD to RELENG_7: Add textdump(4) facility, which provides an alternative form of kernel dump using mechanically generated/extracted debugging output rather than a simple memory dump. Current sources of debugging output are: - DDB output capture buffer, if there is captured output to save - Kernel message buffer - Kernel configuration, if included in kernel - Kernel version string - Panic message Textdumps are stored in swap/dump partitions as with regular dumps, but are laid out as ustar files in order to allow multiple parts to be stored as a stream of sequentially written blocks. Blocks are written out in reverse order, as the size of a textdump isn't known a priori. As with regular dumps, they will be extracted using savecore(8). One new DDB(4) command is added, "textdump", which accepts "set", "unset", and "status" arguments. By default, normal kernel dumps are generated unless "textdump set" is run in order to schedule a textdump. It can be canceled using "textdump unset" to restore generation of a normal kernel dump. Several sysctls exist to configure aspects of textdumps; debug.ddb.textdump.pending can be set to check whether a textdump is pending, or set/unset in order to control whether the next kernel dump will be a textdump from userspace. While textdumps don't have to be generated as a result of a DDB script run automatically as part of a kernel panic, this is a particular useful way to use them, as instead of generating a complete memory dump, a simple transcript of an automated DDB session can be captured using the DDB output capture and textdump facilities. This can be used to generate quite brief kernel bug reports rich in debugging information but not dependent on kernel symbol tables or precisely synchronized source code. Most textdumps I generate are less than 100k including the full message buffer. Using textdumps with an interactive debugging session is also useful, with capture being enabled/disabled in order to record some but not all of the DDB session.