Cannot build the Mips 32 bit kernel

[Patrick Mahan]

Juli Mallett wrote:
> On Thu, Aug 26, 2010 at 16:37, Patrick Mahan <pmahan at adaranet.com> wrote:
>> We build for mips o32 under 8.0 and our kernel (before we insert the
>> rootfile system) is
>>
>> -rwxr-xr-x  1 pmahan  pmahan  38155521 Aug 24 19:22 kernel.octeon.32
>>
>> Where when we build it off of head we are seeing
>>
>> -rwxr-xr-x  1 pmahan  pmahan  243364423 Aug 26 09:45 kernel.octeon.32
>>
>> ~38 Mbytes versus ~243 Mbytes
>>
>> a 6x increase in size.  So I was playing around with the configuration
>> file to decide what to leave out.
> 
> That must be either some difference in allocating space for the root
> filesystem or related to having a lot of debugging info and not
> stripping the one from HEAD.  The Cavium Simple Executive (I don't
> know if the proprietary port you're using uses it or not) adds some
> bloat, but nothing like that much.  My kernels, n64 and o32 both, are
> around 8M.  I'm not embedding any sort of root filesystem.

Okay, problem solved, pilot error (sort of :-p).

It was a case of allocating space for the root filesystem.  We have
build scripts that are suppose to winnow down the stuff put into
world/ after we finish a 'buildworld'.  This winnowing reduces the
overall size of the root filesystem.  The script then compares the
size of the created filesystem image to the value of MD_ROOT_SIZE
in OCTEON1-32 and if it is too small, increase it to the correct
size and rebuild the kernel.

It seems that our initial build, the root filesystem was not reduced
in size and this caused MD_ROOT_SIZE to be set to a really large size
and subsequent builds do not reduce the size of MD_ROOT_SIZE thus
the resultant kernel builds were too large.  It wasn't till I went
back and pulled a fresh checkout and carefully ran our build scripts
one at a time that I figured this out.

I've got some code that is not ready for prime time for building the
embedded root filesystem more like how linux uses its initramfs.  This
method does require messing with a large array in place to hold the
root filesystem.  Instead, it will be captured in its own data section.

Patrick