Re: EdgeRouter Pro supported? Strange FP problems

[Markos Chandras <Markos.Chandras@imgtec.com>]

On 07/22/2014 03:33 PM, Rob Kendrick wrote:
> 
>> What FPU problem are you seeing exactly? Could you show us a log for the
>> failure? Can you post a simple test case which will allow someone to
>> reproduce it?
> 
> A strange problem with awk (substr() doesn't work in either gawk or
> mawk).  I've tried binaries of awk that I've built myself, and binaries
> from Debian.  They all fail with my kernel, work fine with the 3.4
> kernel (with a load of Cavium patches) that ship with the EdgeRouter
> Pro.
> 
> I can see it with this awk script:
> 
> {
>   line = $ 0
>   prefix = substr(line, 1, 3)
>   suffix = substr(line, 9)
>   print "prefix is '" prefix "'"
>   print "suffix is '" suffix "'"
> }
> 
> execute with `echo "foo bar baz" | awk -f test.awk`.  With gawk, I get
> both outputs being "foo bar baz" and with mawk "".  Correct answers
> occur when using the shipped 3.4.
> 
> When you run gawk in linting mode, you get amusing errors like:
> 	warning: substr: length 3 too big for string indexing,
> 	truncating to 1.84467e+19

there have been quite a few FPU changes in 3.16. I am able to reproduce
the problem on EdgeRouter (non pro) but the result is not the same as
yours. The output using the 'gawk' is:

prefix is ''
suffix is 'baz'

a quick bisect between v3.15 and v3.16-rc1, which is the first tag with
all the new FPU changes, leads to the following bad commit:

08a07904e182895e1205f399465a3d622c0115b8
MIPS: math-emu: Remove most ifdefery.

Reverting the commit is not trivial unfortunately. Perhaps you could use
a v3.15 kernel for now (assuming it boots on that board) or perhaps use
an earlier revision before this bad commit (eg
9e8bad1f9c0370b2635175b34d6151b90a53da5c, which boots and your test
works for me)

[root@buildroot ~]# uname -a
Linux buildroot 3.15.0-rc5-00171-g9e8bad1f9c03 #1280 SMP PREEMPT Tue Jul
22 16:36:19 BST 2014 mips64 GNU/Linux
[root@buildroot ~]# echo "foo bar baz" | awk -f awk-test
prefix is 'foo'
suffix is 'baz'

I have CC'd Ralf who is the author of the commit. Ralf any idea?

-- 
markos