10.13. Memory region attributes
Memory region attributes allow you to describe special handling
required by regions of your target's memory. gdb uses attributes
to determine whether to allow certain types of memory accesses; whether to
use specific width accesses; and whether to cache target memory.
Defined memory regions can be individually enabled and disabled. When a
memory region is disabled, gdb uses the default attributes when
accessing memory in that region. Similarly, if no memory regions have
been defined, gdb uses the default attributes when accessing
all memory.
When a memory region is defined, it is given a number to identify it;
to enable, disable, or remove a memory region, you specify that number.
- mem lower upper attributes…
Define memory region bounded by lower and upper with
attributes attributes…. Note that upper == 0 is a
special case: it is treated as the the target's maximum memory address.
(0xffff on 16 bit targets, 0xffffffff on 32 bit targets, etc.)
- delete mem nums…
Remove memory regions nums….
- disable mem nums…
Disable memory regions nums….
A disabled memory region is not forgotten.
It may be enabled again later.
- enable mem nums…
Enable memory regions nums….
- info mem
Print a table of all defined memory regions, with the following columns
for each region.
- Memory Region Number, Enabled or Disabled.
Enabled memory regions are marked with y.
Disabled memory regions are marked with n.
- Lo Address
The address defining the inclusive lower bound of the memory region.
- Hi Address
The address defining the exclusive upper bound of the memory region.
- Attributes
The list of attributes set for this memory region.
10.13.1. Attributes
10.13.1.1. Memory Access Mode
The access mode attributes set whether gdb may make read or
write accesses to a memory region.
While these attributes prevent gdb from performing invalid
memory accesses, they do nothing to prevent the target system, I/O DMA,
etc. from accessing memory.
- ro
Memory is read only.
- wo
Memory is write only.
- rw
Memory is read/write. This is the default.
10.13.1.2. Memory Access Size
The acccess size attributes tells gdb to use specific sized
accesses in the memory region. Often memory mapped device registers
require specific sized accesses. If no access size attribute is
specified, gdb may use accesses of any size.
- 8
Use 8 bit memory accesses.
- 16
Use 16 bit memory accesses.
- 32
Use 32 bit memory accesses.
- 64
Use 64 bit memory accesses.
10.13.1.3. Data Cache
The data cache attributes set whether gdb will cache target
memory. While this generally improves performance by reducing debug
protocol overhead, it can lead to incorrect results because gdb
does not know about volatile variables or memory mapped device
registers.
- cache
Enable gdb to cache target memory.
- nocache
Disable gdb from caching target memory. This is the default.
