[OpenWrt-Devel] [PATCH] mtd: correct/change warning text about partition split / read-only status

[Hannu Nyman]

Since the kernel/rootfs split handling was modified 2 years ago by r37283 ( 
https://dev.openwrt.org/changeset/37283 ) and by the subsequent checkins, 
users have seen rather scary mtd errors in the log at every boot. The message 
ends "-- forcing read-only", which looks a bit error-like. That error has 
been mentioned in some forum threads, when users have noticed this message 
instead of some actual error.

[    2.940000] 0x000000070000-0x000000ff0000 : "firmware"
[    2.970000] 2 netgear-fw partitions found on MTD device firmware
[    2.970000] 0x000000070000-0x000000188440 : "kernel"
[    2.980000] mtd: partition "kernel" must either start or end on erase 
block boundary or be smaller than an erase block -- forcing read-only
[    2.990000] 0x000000188440-0x000000ff0000 : "rootfs"
[    2.990000] mtd: partition "rootfs" must either start or end on erase 
block boundary or be smaller than an erase block -- forcing read-only
[    3.010000] mtd: device 4 (rootfs) set to be root filesystem
[    3.010000] 1 squashfs-split partitions found on MTD device rootfs
[    3.020000] 0x000000660000-0x000000ff0000 : "rootfs_data"

The error text 'mtd: partition "kernel" must either start or end on erase 
block boundary or be smaller than an erase block -- forcing read-only' 
originates from 6 years ago, when nbd checked in r17658 to kernel 2.6.30.
https://dev.openwrt.org/changeset/17658
https://dev.openwrt.org/browser/trunk/target/linux/generic-2.6/patches-2.6.30/222-partial_eraseblock_write.patch?rev=17658

At that time, this message was rarely shown, as it was normal to have padding 
after kernel, so that rootfs started at the next block boundary. Currently 
many platforms have kernel & rootfs tightly packed without padding in 
between, so the message is shown quite frequently.

Additionally, I think that the original warning message has a logical fault: 
the first "or" should be "and". It should say "must either start AND end on 
erase block boundary or be smaller than an erase block".  (otherwise 'kernel' 
should not cause the warning message as it starts at a boundary...). The 
logic in 411-mtd-partial_eraseblock_write.patch is pretty hard to follow, but 
that is my reading about the correct reasoning.
https://dev.openwrt.org/browser/trunk/target/linux/generic/patches-3.18/411-mtd-partial_eraseblock_write.patch 


I propose that the message class is changed from a kernel warning to a kernel 
info message and the text is changed to be less scary: 'partition "kernel" is 
read-only: it does not start and end at erase block boundary and is larger 
than a single block'

[    2.970000] 2 netgear-fw partitions found on MTD device firmware
[    2.970000] 0x000000070000-0x000000188440 : "kernel"
[    2.980000] mtd: partition "kernel" is read-only: it does not start and 
end at erase block boundary and is larger than a single block
[    2.990000] 0x000000188440-0x000000ff0000 : "rootfs"
[    2.990000] mtd: partition "rootfs" is read-only: it does not start and 
end at erase block boundary and is larger than a single block


I would prefer to shorten the message even more, but I didn't invent a 
suitable short but informative wording. (Althoug as this is currently most 
often just an informative notice, I am not quite sure if the logic needs to 
be explained quite that closely in the message.)

Signed-off-by: Hannu Nyman <hannu.nyman at iki.fi>

-------------- next part --------------
--- target/linux/generic/patches-3.18/411-mtd-partial_eraseblock_write.patch
+++ target/linux/generic/patches-3.18/411-mtd-partial_eraseblock_write.patch
@@ -126,7 +126,7 @@
 +			slave->mtd.erasesize = slave->mtd.size;
  	}
 +	if ((slave->mtd.flags & (MTD_ERASE_PARTIAL|MTD_WRITEABLE)) == MTD_ERASE_PARTIAL)
-+		printk(KERN_WARNING"mtd: partition \"%s\" must either start or end on erase block boundary or be smaller than an erase block -- forcing read-only\n",
++		printk(KERN_INFO"mtd: partition \"%s\" is read-only: it does not start and end at erase block boundary and is larger than a single block\n",
 +				part->name);
  
  	slave->mtd.ecclayout = master->ecclayout;
--- target/linux/generic/patches-4.0/411-mtd-partial_eraseblock_write.patch
+++ target/linux/generic/patches-4.0/411-mtd-partial_eraseblock_write.patch
@@ -126,7 +126,7 @@
 +			slave->mtd.erasesize = slave->mtd.size;
  	}
 +	if ((slave->mtd.flags & (MTD_ERASE_PARTIAL|MTD_WRITEABLE)) == MTD_ERASE_PARTIAL)
-+		printk(KERN_WARNING"mtd: partition \"%s\" must either start or end on erase block boundary or be smaller than an erase block -- forcing read-only\n",
++		printk(KERN_INFO"mtd: partition \"%s\" is read-only: it does not start and end at erase block boundary and is larger than a single block\n",
 +				part->name);
  
  	slave->mtd.ecclayout = master->ecclayout;
-------------- next part --------------
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