access mode address-expression [, byte-size-expression]

The memory specified by address-expression has been accessed.

mode specifies how the memory was accessed. It can be composed of one or all of the letters:

r

The memory at the specified address has been read.

w

The memory has been written to.

x

The memory has been executed.

mode can also contain either of the following:

a

Stops the process after the access (default).

b

Stops the process before the access.

In both cases the program counter will point at the offending instruction. The “before” and “after” refer to the side effect.

address-expression is any expression that can be evaluated to produce an address. If you give a symbolic expression, the size of the region to be watched is automatically deduced; you can override it by specifying byte-size-expression. You can also use nonsymbolic, typeless address expressions; in which case, the size is mandatory. For example:

stop access w 0x5678, sizeof(Complex)

The access command has the limitation that no two matched regions may overlap.

The access event specification is a replacement for the modify event specification.