7.122 .weak names

This directive sets the weak attribute on the comma separated list of symbol names. If the symbols do not already exist, they will be created.

On COFF targets other than PE, weak symbols are a GNU extension. This directive sets the weak attribute on the comma separated list of symbol names. If the symbols do not already exist, they will be created.

On the PE target, weak symbols are supported natively as weak aliases. When a weak symbol is created that is not an alias, GAS creates an alternate symbol to hold the default value.