diff options
Diffstat (limited to 'gdb/doc')
| -rw-r--r-- | gdb/doc/ChangeLog | 5 | ||||
| -rw-r--r-- | gdb/doc/gdb.texinfo | 14 |
2 files changed, 18 insertions, 1 deletions
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog index 8ef6cba..a01d545 100644 --- a/gdb/doc/ChangeLog +++ b/gdb/doc/ChangeLog @@ -1,3 +1,8 @@ +2016-06-09 Toshihito Kikuchi <k.toshihito@yahoo.de> + + * gdb.texinfo (Examining Memory): Document negative repeat + count in the 'x' command. + 2016-06-06 Simon Marchi <simon.marchi@ericsson.com> * gdb.texinfo (GDB/MI Async Records): Document method and diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 1da81a1..6e2b493 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -9295,7 +9295,8 @@ Several commands set convenient defaults for @var{addr}. @table @r @item @var{n}, the repeat count The repeat count is a decimal integer; the default is 1. It specifies -how much memory (counting by units @var{u}) to display. +how much memory (counting by units @var{u}) to display. If a negative +number is specified, memory is examined backward from @var{addr}. @c This really is **decimal**; unaffected by 'set radix' as of GDB @c 4.1.2. @@ -9350,6 +9351,10 @@ starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four words (@samp{w}) of memory above the stack pointer (here, @samp{$sp}; @pxref{Registers, ,Registers}) in hexadecimal (@samp{x}). +You can also specify a negative repeat count to examine memory backward +from the given address. For example, @samp{x/-3uh 0x54320} prints three +halfwords (@code{h}) at @code{0x54314}, @code{0x54328}, and @code{0x5431c}. + Since the letters indicating unit sizes are all distinct from the letters specifying output formats, you do not have to remember whether unit size or format comes first; either order works. The output @@ -9366,6 +9371,13 @@ follow the last instruction that is within the count. The command @code{disassemble} gives an alternative way of inspecting machine instructions; see @ref{Machine Code,,Source and Machine Code}. +If a negative repeat count is specified for the formats @samp{s} or @samp{i}, +the command displays null-terminated strings or instructions before the given +address as many as the absolute value of the given number. For the @samp{i} +format, we use line number information in the debug info to accurately locate +instruction boundaries while disassembling backward. If line info is not +available, the command stops examining memory with an error message. + All the defaults for the arguments to @code{x} are designed to make it easy to continue scanning memory with minimal specifications each time you use @code{x}. For example, after you have inspected three machine |