On Tue, Mar 14, 2017 at 05:11:06PM +0530, Vignesh R wrote:
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On Friday 10 March 2017 11:32 PM, Tom Rini wrote:
Yes, I agree that initial DT layout of 512K may not have been good design, but it would be good to have an agreeable way of fixing up MTD partitions when there is overflow. So, is fdt_fixup_mtdparts() preferred approach?
You make a good point about fdt_fixup_mtdparts() being non-trivial to have happen correctly in all cases above, so OK, lets put that aside. I'll also accept that previous best wisdom of not shoving tons of stuff into the cmdline, rather than passing it in the device tree, isn't correct anymore.
But the big, un-tackled problem is that the old DT layout is failing because we're constantly increasing the number of full linux DTB files we're including in an image and thus increasing the size of our blob every time. We need to stop and think and maybe design things differently. Perhaps it's time for more platforms to have a spot on their storage where the DT is supposed to be, and we only use a fall back one that's included in U-Boot if it's not found? Franklin already posted a patch to have something kind-of similar be able to happen (which is to say, go from a generic DTB to the correct-for-the-HW one).
I agree that DTB files are making u-boot image bulky. But it does not seem to be problem due to addition of DT alone. For example SPI boot image on K2 platform is two stage SPL+U-Boot combined into one single image u-boot-spi.gph which is about 555K. General boot image u-boot.bin is about 491K and u-boot-nodtb.bin is 432K. So even w/o dtbs SPI image may overflow and its because of new code/framework changes.
Which platform exactly? I don't see anything today that's quite that large. And can we not move towards the "normal" method of SPL loading the u-boot.img (or FIT) from? I guess the current architecture here is confusing me.
Regardless, I still see the DT problem as the bigger one long term, and dra7xx shows that. And I agree we need to re-size how the flash is partitioned.
There is similar issue with dra7xx where flash partition for SPL is running out due to addition of new code.
The DRA flash partition is, and should be fine because we have the ROM-mandated limits and don't need to include U-Boot with the SPL image. The main U-Boot image however is growing and that is a DTB problem. The difference here between -nodtb and the .img (FIT) with all of the DTBs is over 300KiB. And that's mostly linear growth when compared with the single-DTB case.