[LEDE-DEV] [PATCH] cns3xxx: backport upstream SPI Flash partition sizes

[Tim Harvey]

On Thu, Sep 15, 2016 at 7:36 AM, Tim Harvey <tharvey at gateworks.com> wrote:
> On Thu, Sep 15, 2016 at 4:03 AM, Felix Fietkau <nbd at nbd.name> wrote:
>> On 2016-09-15 12:16, Felix Fietkau wrote:
>>> On 2016-09-15 11:34, Koen Vandeputte wrote:
>>>> As indicated by Tim Harvey:
>>>>
>>>> The 4.4 kernel is not easily sized down to below the 1.5MB limit
>>>> imposed by the SPI flash MTD partition mapping. Increase this
>>>> to 2MB where it is for NOR flash devices.
>>>> Additionally add a check that ensures the kernel fits within
>>>> the 2MB limit.
>>>>
>>>> This resolves boot issues on SPI based boards such as the GW2380/82.
>>>>
>>>> https://github.com/Gateworks/openwrt/commit/17b860f32fe5739042445eb852109682d6ff7d99
>>>>
>>>> Signed-off-by: Koen Vandeputte <koen.vandeputte at ncentric.com>
>>> I'm now working on the approach that I encouraged Tim to take when this
>>> issue came up last. I think simply bumping the hardcoded kernel/rootfs
>>> split partition sizes is a hack at best, my solution involves using
>>> mtdsplit to make the kernel/rootfs split dynamic, like on other platforms.
>>> From what I can tell, the old sysupgrade script is written in a way that
>>> the image format changes will not break sysupgrade from old firmware to
>>> new and vice versa.
>> It's done now and pushed to my staging tree:
>> https://git.lede-project.org/?p=lede/nbd/staging.git;a=commit;h=aa58ee42c93136a8e158ef317cad20806001c039
>>
>> Please take a look at the commit description, test it, and let me know
>> what you think.
>>
>> - Felix
>

Felix,

I like the 'idea' of using mtdsplit (very clean) however this break's
the ability to downgrade firmware. If I take an old firmware image (a
version of OpenWrt prior to cns3xxx moving to the 4.4 kernel which
became too large to fit in the hard-coded mtd partitions chosen long
ago) I can upgrade with the new mtdsplit sysupgrade however if I then
try to downgrade to a non-mtdsplit sysupgrade image from the older
kernel it will fail in the image check with 'Invalid image type. Image
check 'platform_check_image' failed.'. I suppose if we wanted to
support upgrade and downgrade we would need to keep logic in
platform.sh to deal with the old partitioning.

I suppose sysupgrade != sysdowngrade so maybe I should care about
downgrading without JTAG?

Also, to create JTAG images I need the root.squashfs and the uImage so
we need to keep those in the BIN_DIR (although we don't need to pad
them... I can do that in script that creates JTAG'able images).

Regards,

Tim