RE: M0 and M3 patches in linaro toolchains

Joey Ye <[email protected]> writes:

> I'm not sure what blocked M0. There are a few things suspicious:
> * Which C library is used? The one gcc-arm-embedded works, and the only one
> I know works for Cortex-M, is newlib. Other than that, good luck :-(

I'm using pdclib, which is not the best solution in most ways except
that it's very portable :-)

> Overall, sharing a source between arm-linux and arm-none-eabi sounds a good
> idea, but library can be the road blocker. As bare-metal version should use
> newlib and linux use glibc, it is not that straight-forward as assumed.
> Please be aware of this extra burden.

I've packaged a bare gcc which doesn't reference *any* libc, allowing
the user to select the best libc for their project. We could separately
package both newlib and pdclib for various targets if we liked?

> Alternative approach is just grab the gcc-arm-embedded 4.8, which will be
> ready by Q4, and build it for debian. It will be straight forward as it is
> already built and released by launchpad as debian package and distributed as
> PPA. Also it will behavior the same as any other gcc-arm-embedded running on
> other linux distribution and Windows, which have been downloaded 100,000
> copies.

I've grabbed the 4.7 q2 version for now and packaged that; I looked at
the diffs from the 4.8 embedded tree to the current Debian 4.8 gcc
sources and they were huge (700k line patch). I didn't analyze that
further; perhaps it's mostly spurious?

> Again, I'm not sure what blocked M0. I'm interested to know more details
> about this.

I can look at this in more detail if desired. I was getting a CPU fault
(presumably from executing some non -M0 instructions) with the Debian
bits compiled in precisely the same way as I am now successfully
building the Linaro -q2 bits.

-keith

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