Dear Masahiro,
In message 20140404114250.5C15.AA925319@jp.panasonic.com you wrote:
Correct. In some (really old) kernel versions this was the way to pass this information to the kernel, so we neede dit there.
I suspect the reason it is in global_data is that the bd_t structure doesn't exist until some time after the console is started up, so it wouldn't be possible to do serial output otherwise.
Also correct.
Thanks. Sadly, it looks like we should keep both of the two.
I'm not so sure. As mentioned, this was used in really old kernel versions only. I remember it for the Power archtecture, where only the pre-devicetree kernel versions (i. e. 2.4.x) used this. OK, I know of a number of projeects which are still using such old kernbel versions, but these are also using ancient U-Boot versions.
I don't think we have to keep support for ancient kernels in current U-Boot. Eventually we may drop it.
Best regards,
Wolfgang Denk