[Letux-kernel] Raspi3B+ support

H. Nikolaus Schaller hns at goldelico.com
Mon Jan 7 17:02:27 CET 2019


> Am 07.01.2019 um 16:52 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> 
>> Am 07.01.2019 um 16:33 schrieb Andreas Kemnade <andreas at kemnade.info>:
>> 
>> Hi,
>> 
>>> It might have something to do with the undocumented -@ option of dtc (the command line dtc from Debian package doesn't even understand it).
>>> Or there is something wrong in choosing the console device name (there are no aliases for serial0/1 in mainline DTS).
>>> 
>> dtc --help
>> 
>> clearly lists and documents it, at least the version from kernel.
> 
> Well, yes, *only* the version from kernel. What I mean is that I did not find it with google "man dtc". And AFAIK the kernel does not have its own man pages for its tools. So I simply didn't expect that the Kernel is adding its own options and features but hiding in lower quality documentation. BTW: Documentation//devicetree/booting-without-of.txt does mention only some options.
> 
> And since I am cross-compiling it is a little more difficult to use the kernel based version (especially if I currently compile something else) than trying the native one on some Letux device:
> 
> root at letux:~# dpkg -l | fgrep device-tree-compiler
> ii  device-tree-compiler    1.4.0+dfsg-1    armhf    Device Tree Compiler for Flat Device Trees
> root at letux:~# dtc -v
> Version: DTC 1.4.0
> root at letux:~# dtc --help
> Usage: dtc [options] <input file>
> 
> Options: -[qI:O:o:V:d:R:S:p:fb:i:H:sW:E:hv]
>  -q, --quiet                
> 	Quiet: -q suppress warnings, -qq errors, -qqq all
>  -I, --in-format <arg>      
> 	Input formats are:
> 		dts - device tree source text
> 		dtb - device tree blob
> 		fs  - /proc/device-tree style directory
>  -o, --out <arg>            
> 	Output file
>  -O, --out-format <arg>     
> 	Output formats are:
> 		dts - device tree source text
> 		dtb - device tree blob
> 		asm - assembler source
>  -V, --out-version <arg>    
> 	Blob version to produce, defaults to %d (for dtb and asm output)
>  -d, --out-dependency <arg> 
> 	Output dependency file
>  -R, --reserve <arg>        
> 	tMake space for <number> reserve map entries (for dtb and asm output)
>  -S, --space <arg>          
> 	Make the blob at least <bytes> long (extra space)
>  -p, --pad <arg>            
> 	Add padding to the blob of <bytes> long (extra space)
>  -b, --boot-cpu <arg>       
> 	Set the physical boot cpu
>  -f, --force                
> 	Try to produce output even if the input tree has errors
>  -i, --include <arg>        
> 	Add a path to search for include files
>  -s, --sort                 
> 	Sort nodes and properties before outputting (useful for comparing trees)
>  -H, --phandle <arg>        
> 	Valid phandle formats are:
> 		legacy - "linux,phandle" properties only
> 		epapr  - "phandle" properties only
> 		both   - Both "linux,phandle" and "phandle" properties
>  -W, --warning <arg>        
> 	Enable/disable warnings (prefix with "no-")
>  -E, --error <arg>          
> 	Enable/disable errors (prefix with "no-")
>  -h, --help                 
> 	Print this help and exit
>  -v, --version              
> 	Print version and exit
> root at letux:~# 

Ok, here is the --help diff:

iMac:Linux hns$ diff kernel.help debian.help
3c3
< Options: -[qI:O:o:V:d:R:S:p:a:fb:i:H:sW:E:@AThv]
---
> Options: -[qI:O:o:V:d:R:S:p:fb:i:H:sW:E:hv]
19c19
< 	Blob version to produce, defaults to 17 (for dtb and asm output)
---
> 	Blob version to produce, defaults to %d (for dtb and asm output)
23c23
< 	Make space for <number> reserve map entries (for dtb and asm output)
---
> 	tMake space for <number> reserve map entries (for dtb and asm output)
28,29d27
<   -a, --align <arg>          
< 	Make the blob align to the <bytes> (extra space)
47,52d44
<   -@, --symbols              
< 	Enable generation of symbols
<   -A, --auto-alias           
< 	Enable auto-alias of labels
<   -T, --annotate             
< 	Annotate output .dts with input source file and line (-T -T for more details)
iMac:Linux hns$ 

Funnily, there are typos in the help message of the debian package.

Nevertheless the description of -@ "Enable generation of symbols" is not very helpful. Why would one enable that? What happens if not? What are "symbols" etc. Questions over questions...

But for getting the Raspi boot, trial and error will suffice :)

> Anyways, is there a patch for the raspberry to enable -@ or how do I have to pass it to kernel-make so that DTC makes use of it? But only for RasPi and perhaps BeagleBone (where it appears to be also useful). I simply don't find good enough documentation to solve that myself.
> 
> BR,
> NIkolaus
> 
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