[LEDE-DEV] [PATCH v2 2/8] apm821xx: add support for the Cisco Meraki MR24

[Felix Fietkau]

On 2016-07-14 23:09, Christian Lamparter wrote:
> On Thursday, July 14, 2016 10:02:36 PM CEST Felix Fietkau wrote:
>> On 2016-07-14 21:39, Christian Lamparter wrote:
>> > This is mostly because with subtargets, it's possible to have different
>> > kernel configs.
>> > 
>> > MyBook Live is somewhat unique compared to the MR24 or the WNDR4700. It has to
>> > do without any flash (the 512Kb flash on the MBL only contains the u-boot). 
>> > The target's boot and rootfs has to be located on the SATA drive, so the MBL
>> > needs to have the ext2/4 built-in to boot. (WD's u-boot requires the bootfs 
>> > to be ext2. We could do without it, if we didn't care about sysupgrade).
>> > 
>> > The problem with having a shared target for MR24 and WNDR4700 is that the they
>> > have different hard-coded addresses (CONFIG_PPC_EARLY_DEBUG_44x_PHYSLOW) for 
>> > the early console. Other than that, there is AFICT no reason.
>> > 
>> > So, what's the plan? Have a NAS and ROUTER subtarget? And forget about the early
>> > console?
>> I don't think early console is worth having subtargets for. 
> Having individual kernel-configs for targets would solve this.
Individual kernel-configs would again increase the number of build
configurations, so that's not an option.

>> And regarding router vs nas: how much flash does the router have? Can it
>> handle the extra stuff that NAS devices need in their kernel config?
> The WNDR4700's kernel's uimage can be max 2M. Currently a lzma'd uimage
> is at 1.5M. ext4 built-in will add another 150k. dm and md 
OK, I guess it makes sense to have router/nas subtargets then.

>> Having unnecessary extra subtargets wastes resources on snapshot builds
>> and releases, so I want as few of them as possible.
> I've looked into a shared subtarget. One problem that came up was with the
> "ext4" [0], "ramdisk" [1], squashfs, nand features in the FEATURES list.
> 
> [0] MR24 will now select the CONFIG_TARGET_ROOTFS_EXT4FS option by
> default and generate a useless ext4 rootfs. (Default 48M)
In the image building code, a Device/* section can override the
filesystems that are built for the device, using the FILESYSTEMS variable.

> Note: The WNDR4700 will also generate a ext4 image. However, since it
>       has the option for a HDD, a rootfs on the HDD is do-able with 
>       some additional work (e.g.:  cmdline).
> 
> [1] MyBook Live will now generate useless ramdisk and squashfs images.
ramdisk images might still be useful.

- Felix