You can use the commands
restore to copy data between target memory and a file. The
append commands write data to a file, and the
restore command reads data from a file back into the inferior’s
memory. Files may be in binary, Motorola S-record, Intel hex, or
Tektronix Hex format; however, GDB can only append to binary
dump [format] memory filename start_addr end_addr
dump [format] value filename expr
Dump the contents of memory from start_addr to end_addr, or the value of expr, to filename in the given format.
The format parameter may be any one of:
Raw binary form.
Intel hex format.
Motorola S-record format.
Tektronix Hex format.
GDB uses the same definitions of these formats as the GNU binary utilities, like ‘objdump’ and ‘objcopy’. If format is omitted, GDB dumps the data in raw binary form.
append [binary] memory filename start_addr end_addr
append [binary] value filename expr
Append the contents of memory from start_addr to end_addr, or the value of expr, to the file filename, in raw binary form. (GDB can only append data to files in raw binary form.)
restore filename [binary] bias start end
Restore the contents of file filename into memory. The
restore command can automatically recognize any known BFD
file format, except for raw binary. To restore a raw binary file you
must specify the optional keyword
binary after the filename.
If bias is non-zero, its value will be added to the addresses contained in the file. Binary files always start at address zero, so they will be restored at address bias. Other bfd files have a built-in location; they will be restored at offset bias from that location.
If start and/or end are non-zero, then only data between file offset start and file offset end will be restored. These offsets are relative to the addresses in the file, before the bias argument is applied.