On Fri, Sep 30, 2016 at 04:20:10AM +0000, york sun wrote:
On 09/29/2016 08:59 PM, Masahiro Yamada wrote:
2016-09-30 0:47 GMT+09:00 york sun york.sun@nxp.com:
On 09/28/2016 12:17 PM, Simon Glass wrote:
+Masahiro, who may know
Masahiro,
Need some advise on this. How do we deal with duplicated config?
York
On 28 September 2016 at 12:57, york sun york.sun@nxp.com wrote:
On 09/27/2016 10:55 AM, Simon Glass wrote:
Hi York,
On 27 September 2016 at 11:39, york sun york.sun@nxp.com wrote: > Guys, > > I want to discuss to rearrange the current CONFIG_* macros used by > Freescale Layerscape SoCs. We have been encouraged to use CONFIG_SYS_* > macros to define hardware setting, and other CONFIG_* macros for user > setting. Clearly this has changed. Kconfig options are used for most > user settings from now on. I am OK with it. But for existing > CONFIG_SYS_* macros, we need a plan to either move them out of CONFIG_* > name space, or move some to Kconfig, if that makes sense. Since most our > CONFIG_SYS_* macros are cross platforms (including armv7 and armv8), if > using Kconfig option, do we add another mach-fsl folder to host the > Kconfig, or somewhere else? We also have macros cross ARM and PowerPC. > So we either move them out of arch/, or duplicate them for both arch. > > If we move them to another name space, for example SYS_FSL_*, do we want > to move them out of config.h? > > Any suggestion/comment?
I wonder if some of these (the ones that represent actual values rather than enabling functions) can move to device tree, or tables?
While I try to move some options to Kconfig, I have an issue of duplicated names. For example, the MAX_CPUS is used in arch/x86/Kconfig. I know I can put another config with the same name, for example arch/arm/cpu/armv8/fsl-layerscape/Kconfig. The funny thing is when I search for this config option under menuconfig, it shows the location of x86, but showing defined in arch/arm/cpu/armv8/fsl-layerscape/Kconfig. Same thing happens when I try to move an option which is used by both PowerPC and ARM. This is not related to a common driver so I cannot put the option into a driver Kconfig (for example CONFIG_SYS_HAS_SERDES).
Is there a solution for this?
Right. The "Help" in menuconfig is just to display the path to the first Kconfig entry found. The result looks funny if we have multiple entries for the same option name.
I am not pretty sure about this particular case, but there should be general solutions.
(1) Rename the option to avoid name space conflict, e.g.
MAX_CPUS -> FSL_MAX_CPUS (for Freescale SoCs) MAX_CPUS -> X86_MAX_CPUS (for x86)It is a solution, but I don't like it for the reason described below[1].
(2) Unify the Kconfig entry
As in Linux, we do not generally create multiple entries for the same option.
If the option is sensible only for some platforms, the general practice is to use "depends on HAVE_..." to hide the option on unrelated platforms.
If X86 and FSL are the only platforms that have interest in this option, we can save HAVE_... and put them directly in "depends on".
config MAX_CPUS int "Maximum number of CPUs permitted" depends on (SMP && X86) || VENDOR_FSLI am not quite sure about "VENDOR_FSL", so please choose your favorite one like SOC_FSL, PLAT_FSL, ARCH_FSL, or whatever.
This sounds like a bandage. I can go with this if there is no better solution.
If MAX_CPUS has the same meaning in both cases, this isn't imho a bandage but one of the cleanups that was hoped for in moving to Kconfig. We see that a problem is encountered in more than one area more easily and instead of letting N solutions accumulate we get one.
Checking Linux Kconfig, I noticed the NR_CPUS are used in all archs. The difference is only one arch Kconfig is sourced by
source "arch/$SRCARCH/Kconfig"
I tried to do the same for U-Boot, but that will require we put ARCH at the command line of environmental variable. I think we moved away from this syntax. It also has some trouble to to use aarch64 because we put the actual code under arch/arm.
Yeah, we don't want to move in this direction.
[snip]
[1] We have macros shared between PowerPC and ARM for Freescale QorIQ SoCs because they share similar designs at SoC level. Some options can be moved to driver Kconfig to avoid duplication. But there are many options are tied to hardware and they are not related to a common driver. Using the same macro simplifies the code and is easier to maintain. It is preferred to either PowerPC Kconfig, or ARM Kconfig to avoid duplication if we can.
I think this is honestly going to be the hard part, deciding what belongs in a Kconfig'd area and what belongs in a different namespace but that in the end we'll have clearer code for PowerPC and ARM going forward.