NetGDB(4) is a component of a system using a panic-time network stack to
remotely debug crashed FreeBSD kernels over the network, instead of
traditional serial interfaces.
There are three pieces in the complete NetGDB system.
First, a dedicated proxy server must be running to accept connections from
both NetGDB and gdb(1), and pass bidirectional traffic between the two
protocols.
Second, the NetGDB client is activated much like ordinary 'gdb' and
similarly to 'netdump' in ddb(4) after a panic. Like other debugnet(4)
clients (netdump(4)), the network interface on the route to the proxy server
must be online and support debugnet(4).
Finally, the remote (k)gdb(1) uses 'target remote <proxy>:<port>' (like any
other TCP remote) to connect to the proxy server.
The NetGDB v1 protocol speaks the literal GDB remote serial protocol, and
uses a 1:1 relationship between GDB packets and sequences of debugnet
packets (fragmented by MTU). There is no encryption utilized to keep
debugging sessions private, so this is only appropriate for local
segments or trusted networks.
Submitted by: John Reimer <john.reimer AT emc.com> (earlier version)
Discussed some with: emaste, markj
Relnotes: sure
Differential Revision: https://reviews.freebsd.org/D21568
Loosen requirements for connecting to debugnet-type servers. Only require a
destination address; the rest can theoretically be inferred from the routing
table.
Relax corresponding constraints in netdump(4) and move ifp validation to
debugnet connection time.
Submitted by: John Reimer <john.reimer AT emc.com> (earlier version)
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D21482
Add a 'X -s <server> -c <client> [-g <gateway>] -i <interface>' subroutine
to the generic debugnet code. The imagined use is both netdump, shown here,
and NetGDB (vaporware). It uses the ddb(4) lexer, with some new extensions,
to parse out IPv4 addresses.
'Netdump' uses the generic debugnet routine to load a configuration and
start a dump, without any netdump configuration prior to panic.
Loosely derived from work by: John Reimer <john.reimer AT emc.com>
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D21460
Add /i option for machine-parseable CSV output. This allows ready copy/
pasting into more sophisticated tooling outside of DDB.
Add total zone size ("Memory Use") as a new column for UMA.
For both, sort the displayed list on size (print the largest zones/types
first). This is handy for quickly diagnosing "where has my memory gone?" at
a high level.
Submitted by: Emily Pettigrew <Emily.Pettigrew AT isilon.com> (earlier version)
Sponsored by: Dell EMC Isilon
These commands show the route resolved for a specified destination, or
print out the entire routing table for a given address family (or all
families, if none is explicitly provided).
Discussed with: emaste
Differential Revision: https://reviews.freebsd.org/D21510
Currently, the 'thread' command (to switch the debugger to another thread)
only accepts decimal-encoded tids. Use the same parsing logic as 'show
thread <arg>' to accept hex-encoded thread pointers in addition to
decimal-encoded tids.
Document the 'thread' command in ddb.4 and expand the 'show thread'
documentation to cover the tid usage.
Reported by: bwidawsk
Reviewed by: bwidawsk (earlier version), kib (earlier version), markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D16962
We use ps to collect the information of all processes in textdump. But
it doesn't contain process arguments which however sometimes are very
useful for debugging. The new 'a' modifier adds that capability.
While here, remove 'm' modifier from ddb.4. It was in the manual page
from its very first revision, but I could not find any evidence of the
code ever supporting it.
Submitted by: Terry Hu <thu@panzura.com>
Reviewed by: kib
MFC after: 1 week
Sponsored by: Panzura
Differential Revision: https://reviews.freebsd.org/D16603
Implement a ddb function walking the namecache to do this.
Reviewed by: jhb, mjg
Inspired by: gdb macro from jhb (old version)
Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D14898
A follow-up to r322836.
Warnings for the unused declaration were breaking some second tier
architectures, but did not show up in Clang on x86.
Reported by: markj (ddb.4), emaste (declaration)
Sponsored by: Dell EMC Isilon
- Delete empty Li macro uses [1]. This removes some spaces between
the optional command/subcommand arguments.
- Attempt to clarify "show lock" subcommand by being more
terse/direct. This addresses an issue with a contraction [2].
MFC after: 1 week
Reported by: make manlint [1], igor [2]
Reviewed by: wblock
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D9858
db_segsize().
Use db_segsize() to set the default operand/address size for
disassembling. Allow overriding this with the "alternate" display
format /I. The API of db_disasm() should be debooleanized to pass a
more general request (amd64 needs overrides to sizes of 16, 32, and
64, but this commit doesn't implement anything for amd64 since much
larger changes are needed to restore the amd64 disassmbler's support
for non-default sizes).
Fix db_print_loc_and_inst() to ask for the normal format and not the
alternate in normal operation.
This is most useful for vm86 mode, but also works for 16-bit protected
mode.
Use db_segsize() to avoid trying to print a garbage stack trace if %cs
is 16 bits. Print something like the stack trace termination message
for a trap boundary instead.
Document that the alternate format is now useful on i386.
it. This arg is most interesting for the 'break' command where it
never worked, and for the step command where it is powerful but too
fragile to use much.
Give the full syntax of the 'addr' arg for these commands and some
others. Rename it from 'address' for the generic command.
Fix description of how 'count' is supposed to work for the 'break'
command.
Don't (mis)describe the syntax of the comma for the 'step' command.
Expand the description for the generic command.
Give the full syntax for the 'examine' command. It was also missing
the possible values for the modifier.
Fix mdoc syntax error for the 'search' command.
Remove FUD about consequences of not having a trap handler for the
'search' command.
panic string again if set, in case it scrolled out of the active
window. This avoids having to remember the symbol name.
Also add a show callout <addr> command to DDB in order to inspect
some struct callout fields in case of panics in the callout code.
This may help to see if there was memory corruption or to further
ease debugging problems.
Obtained from: projects/vnet
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Reviewed by: jhb (comment only on the show panic initally)
Differential Revision: https://reviews.freebsd.org/D4527
canonical place, and the nit-pickers are welcome to move this
information there with a cross reference.
Differential Review: https://reviews.freebsd.org/D4860
While here also reword 'show buffer' to have an 'addr' argument and to
match other struct documentation.
MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division
Allow textdumps to be called explicitly from DDB.
If "dump" is called in DDB and textdumps are enabled then abort the
dump and tell the user to turn off textdumps.
Add options TEXTDUMP_PREFERRED to turn textdumps on by default.
Add options TEXTDUMP_VERBOSE to be a bit more verbose while textdumping.
Reviewed by: rwatson
MFC after: 2 weeks
Some files keep the SUN4V tags as a code reference, for the future,
if any rewamped sun4v support wants to be added again.
Reviewed by: marius
Tested by: sbruno
Approved by: re
Implement an optional delay to the ddb reset/reboot command.
This allows textdumps to be run automatically with unattended reboots
after a resonable timeout, while still permitting an administrator to
break into debugger if attached to the console at the time of the
event for further debugging. Cap the maximum delay at 1 week to avoid
highly accidental results, and default to 15s in case of problems
parsing the timeout value.
Move hex2dec helper function from db_thread.c to db_command.c to make
it generally available and prefix it with a "db_" to avoid namespace
collisions.
Reviewed by: rwatson
MFC after: 4 weeks
