[Letux-kernel] [PATCH 00/20] A bunch of JZ4730 fixups for letux-kernel

[H. Nikolaus Schaller]

Hi Lubomir,

> Am 30.11.2020 um 07:50 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi Lubomir,
> 
>> Am 28.11.2020 um 16:31 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>>> 
>>> Then I checked out your complete tree, copied the .config to the right location and:
>>> 
>>> 2919423 bytes read
>>> ## Booting image at 80600000 ...
>>> Image Name:   Linux-5.10.0-rc5-letux-l400+
>>> Image Type:   MIPS Linux Kernel Image (gzip compressed)
>>> Data Size:    2919359 Bytes =  2.8 MB
>>> Load Address: 80100000
>>> Entry Point:  8053d0f4
>>> Verifying Checksum ... OK
>>> Uncompressing Kernel Image ... OK
>>> 
>>> Starting kernel ...
>>> 
>>> [    0.000000] Linux version 5.10.0-rc5-letux-l400+ (hns at iMac.fritz.box) (mipsel-linux-gnu-gcc (GCC) 4.9.2, GNU ld (GNU Binutils) 2.25) #4026 PREEMPT Sat Nov 28 14:32:55 CET 2020
>>> [    0.000000] CPU0 revision is: 02d0024f (Ingenic XBurst)
>>> [    0.000000] MIPS: machine is letux400,minipc
>>> [    0.000000] earlycon: jz4740_uart0 at MMIO32 0x10030000 (options '115200n8')
>>> [    0.000000] printk: bootconsole [jz4740_uart0] enabled
>>> [    0.000000] printk: debug: ignoring loglevel setting.
>>> [    0.000000] User-defined physical RAM map overwrite
>>> [    0.000000] Initrd not found or empty - disabling initrd
>>> [    0.000000] cma: Reserved 32 MiB at 0x01000000
>>> ...
>>> 
>>> So there is a subtle difference between your minimalistic tree and the full letux tree which blows up the uImage by ca. 80% and makes it fail to boot.
>>> Have to study this now... But I think we are close.
>> 
>> Seems to be something incompatible in my defconfig.
>> If I merge your tree into mine and use your defconfig it works.
>> The one that is ok for CI20 (of course after switching to JZ4730) fails.
>> 
>> This is now a bisectable problem...
> 
> Yes, it was - partially - bisectable. But it is not a specific CONFIG.
> And not a specific subsystem compiled into the kernel.
> 
> Rather it appears as if there is a limit of ca. 3800000 Bytes for the uImage Data Size.
> Above that there is no sign of activity. Below the kernel boots.
> 
> I have cross-checked and the vmlinux.bin is quite exactly 8 MB in that cases which gets
> compressed into these ca. 3800000 Bytes.
> 
> So please can you
> a) check what happens for your build if you configure for bigger uImage (so that vmlinux.bin is more than 8MB)
>   (e.g. CONFIG_INET, CONFIG_WIRELESS, CONFIG_POSIX_MQUEUE, CONFIG_CGROUPS, CONFIG_NAMESPACES, CONFIG_KEXEC, CONFIG_SUSPEND)
>   until your kernel size goes beyond 3.8 MB resp. 8 MB?
> b) try to boot my smaller uImage-good and the full uImage [1] and look by JTAG why the uncompression fails for the latter?
>   (NOTE: it seems to be jz4730 specific since the CI20 has no problems with bigger uImages)
> c) have ideas why the appended-DTB search algorithm fails? This would not be used for the CI20.

Have you had time to think about this finding?

BR and thanks,
Nikolaus

> 
> BR and thanks,
> Nikolaus
> 
> [1]: https://download.goldelico.com/letux-kernel/letux-5.10-rc5-l400/
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