Type definitions in the self-description can build up composite types from basic building blocks, but can not define fundamental types. Instead, standard identifiers are provided by GDB for the fundamental types. The currently supported types are:
Boolean type, occupying a single bit.
Signed integer types holding the specified number of bits.
Unsigned integer types holding the specified number of bits.
Pointers to unspecified code and data. The program counter and any dedicated return address register may be marked as code pointers; printing a code pointer converts it into a symbolic address. The stack pointer and any dedicated address registers may be marked as data pointers.
Half precision IEEE floating point.
Single precision IEEE floating point.
Double precision IEEE floating point.
The 16-bit brain floating point format used e.g. by x86 and ARM.
The 12-byte extended precision format used by ARM FPA registers.
The 10-byte extended precision format used by x87 registers.
32bit EFLAGS register used by x86.
32bit MXCSR register used by x86.