Hi, On Fri, Dec 26, 2014 at 02:42:07PM +0100, Javier Martinez Canillas wrote: > Hello all, > > On Fri, Dec 26, 2014 at 12:56 PM, Igor Grinberg <grinberg@xxxxxxxxxxxxxx> wrote: > >>>>> Tony, your call. > >>>> > >>>> I think we should move omap2plus_defconfig to be mostly modular and > >>>> usable for distros as a base. Most distros prefer to build almost > >>>> everything as loadable modules. And my preference is that we should > >>>> only keep the minimum rootfs for devices and serial support as > >>>> built-in and rely on initramfs for most drivers. And slowly move > >>>> also the remaining built-in drivers to be loadable modules. > >>>> > >>>> The reasons for having drivers as loadable modules are many. It > >>>> allows distros to use the same kernel for all the devices without > >>>> bloating the kernel. It makes developing drivers easier as just the > >>>> module needs to be reloaded. And loadable modules protect us from > >>>> cross-framework spaghetti calls in the kernel as the interfaces are > >>>> clearly defined. > >>>> > > I do agree with Tony and Felipe that we should try to build as much > stuff as possible as a module instead of built-in to match what > distros do and what has been done for x86 for years. > > However, if that's the case I wonder what's the point of having both > an omap2plus_defconfig and a multi_v7_defconfig? Would it make sense I wonder the same thing, but look at multi_v7_defconfig today. Almost everything is built-in, which makes the kernel image enormous (5.5MiB). > to get rid of the SoC specific configs then and just use the single > ARMv7 defconfig for all SoCs with most of the options enabled as a > module? if people accept switching some of those as modules, sure. I don't mind that at all. I'll still continue to maintain my out-of-tree defconfigs for my boards anyway. It's also very good to have a generic defconfig which will just work with everything I have. > FYI, some time ago I posted a patch to enable SBS-compliant batteries > support as a module for Exynos defconfig and was told to re-spin the > patch and enabling it as built-in instead since the most popular use > case for exynos_defconfig was development and people usually just copy > the kernel binary and not the modules [0]. lol, that's the reason why I don't use multi_v7_defconfig. > So it seems that each ARM SoC community has a different opinion about > how things should be configured and do it differently. I wouldn't be surprised. > >> bullshit, you would never ship a product with omap2plus_defconfig. You'd > >> build your own at which point you would switch SATA to built-in. > > > > There are different opinions but let please try to keep the discussion > constructive and use a polite tone. > > >>> > >>> Right now, we tell our customers that they can use mainline with > >>> omap2plus_defconfig. > >> > >> that's the worst thing you can do. > > > > I'm confused, Felipe said that customers should not base their config > from omap2plus_defconfig but AFAUI Tony's argument is exactly the > opposite, that everything should be configured as a module so distros basing on omap2plus_defconfig is never an issue. Claiming that you're concerned about the extra KiBs for loading initramfs and then saying you ship embedded products with omap2plus_defconfig is BS. > can use omap2plus_defconfig as a base. So, is or is not expected that > people will use omap2plus_defconfig as a base for their own config? I never claimed that people should not use it as a *base*, rather it should not be used to build a product's kernel/modules. Imagine you shipping an embedded product based off of OMAP5 and you add CPSW, QSPI, MUSB, a ton of touchscreen drivers you don't use, several PMIC drivers built-in, etc. It's a waste of space and just bloats that product's zImage. > I think the problem is that there isn't an agreement about what is the > purpose of the per SoC (e.g: oma2plus_defconfig) and the multi_v7 > defconfigs (or at least is not well documented since I could not find > it). So, IMHO this concern should be raised to the ARM SoC maintainers > and there should be an agreement in the ARM community as a whole about > how things should be configured on each defconfig, and all SoCs should > follow the agreed rule. OTOH, the OMAP defconfig is part of the OMAP port and Tony will have the final saying about it, right ? > Otherwise it seems that the motivation for each kconfig symbol enabled > is just to make the workflow of the developer posting the patches > easier and wins whoever shouts louder. it is just to make things easier. In fact, I only enabled AM437x SK's drivers on o2+_dc because I got tired of people telling me that board "doesn't work with mainline" and being completely reluctant to change their defconfig. At that point I talked to Tony and he said "as long as things are added as modules, I don't mind". cheers -- balbi
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