On 06/28/2012 12:18 AM, Hiroshi Doyu wrote: > On Wed, 27 Jun 2012 16:44:14 +0200 > Thierry Reding <thierry.reding at avionic-design.de> wrote: > >>> I think that "coherent_pool" can be used only when the amount of >>> contiguous memory is short in your system. Otherwise even unnecessary. >>> >>> Could you explain a bit more why you want carveout size on per-board basis? >> >> In the ideal case I would want to not have a carveout size at all. >> However there may be situations where you need to make sure some driver >> can allocate a given amount of memory. Having to specify this using a >> kernel command-line parameter is cumbersome because it may require >> changes to the bootloader or whatever. So if you know that a particular >> board always needs 128 MiB of carveout, then it makes sense to specify >> it on a per-board basis. > > Hm...I could understand somewhat;) but DT can also specify "bootargs" > in dts file, which can support per-board-wide spec too, like the above > sum of carveout needed from all drivers. I just want to avoid > introducing a new parameter additionaly if we can make use of the > existing mechanism.
The bootargs in the DT file is usually provided by (over-written by) the bootloader. If we start requiring lots of random kernel command-line arguments, that makes it more effort for the user of the bootloader (e.g. distribution bootloader scripts, etc.) to create the kernel command-line. I'd prefer to avoid that as much as possible. That said, using a standardized command-line option that is (or will be) used by all (ARM?) SoCs for the same purpose is reasonable, because there's commonality there.