On 11 November 2014 16:22, Joey Ye <joey.ye...@gmail.com> wrote: > Markus, > > -mmcu probably will not work for ARM architectured MCUs. Reason are > * Confusion. -mcpu is encouraged and already widely used for ARM > architectures. Introducing -mmcu will be very confusing.
It' just a matter of bundling specifications. -mcpu specifies an architecture and tuning option. -mmcu specifies that (it you have an -mcpu option, you best translate it to that, otherwise you can skip that step), plus additional things that pertain the the parts an mcu consists of besides an mcu. > * Expensive effort. Either supporting none, or supporting all. There > are large number of MCUs from ARM eco-system partners. Supporting all > of them is a large project. > * Maintance nightmare. Having GCC developers to input and maintain > vendor specific configurations is inefficient and error-prone. > * Failed schedule dependence. Having -mmcu actually means whenever > there is a new MCU introduced into market, GCC has to be updated to > describe it. Given GCC's release cycle (once per year) and the > frequency of MCU release (could be tens each year), GCC will never be > able to catch up. These kinds of issues were why I re-implemented the avr -mmcu option with the SELF_SPEC mechanism to read a device-specific spec file. As long as a new mcu can be described with the existing toolchain facilities (e.g. a new combination of existing I/O support, some different parameters describing RAM / flash sizes), a new spec file can be distributed together with a few hardware-specific library/crt files to support a new mcu with an existing compiler. > Further more all the board/MCU specific configurations are already > described in CMSIS and variant of GUI based toolchain for ARM MCU. > Replicating then in GCC does not sounds a right thing to do for me. Yes, better to have a script that translates this info into a suitable spec file and copies any required files in the appropriate installation places. Not sure what kind of Copyright/licensing issues that would entail, though.
