import xyz

class ArmToolchain(xyz.BuildProtocol):
    group_only = True
    pkg_name = 'arm-toolchain'
    supported_targets = ['arm-none-eabi']
    deps = [('gcc', {'target': 'arm-none-eabi'}),
            ('binutils', {'target': 'arm-none-eabi'})]

rules = ArmToolchain()

import xyz

class ArmToolchain(xyz.BuildProtocol):
    group_only = True
    pkg_name = 'arm-toolchain'
    supported_targets = ['arm-none-eabi']
    deps = [('gcc', {'target': 'arm-none-eabi'}),
            ('binutils', {'target': 'arm-none-eabi'}),
            ('gdb', {'target': 'arm-none-eabi'})
            ]

rules = ArmToolchain()

Add gdb to the toolchain