[Buildroot] [Bug 10471] New: Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[Buildroot] [Bug 10471] New: Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

            Bug ID: 10471
           Summary: Building a  mipsel kernel format vmlinuz (+ gzip +
                    initrd) generates non-compressed, non-bootable image
           Product: buildroot
           Version: 2017.02
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: major
          Priority: P5
         Component: Other
          Assignee: unassigned at buildroot.uclibc.org
          Reporter: a.enchevich at gmail.com
                CC: buildroot at uclibc.org
  Target Milestone: ---

Created attachment 7376
  --> https://bugs.busybox.net/attachment.cgi?id=7376&action=edit
My buildroot's .config file

I have sources + images provided by Broadcom for their 7362a0 set top box
boards. The kernel image there is has initrd linked in and is:

$ ls -l 
-rw-r--r-- 1  me users  5669240 Sep 20 17:52 vmlinuz-initrd-7362a0

$ file vmlinuz-initrd-7362a0
vmlinuz-initrd-7362a0: gzip compressed data, last modified: Wed Sep 20 14:52:20
2017, max compression, from Unix

So the vmlinuz that works is about 5.7MB, gzipped, with the initrd.

 = = =

When I try generating a vmlinuz kernel in buildroot, however, I am getting a
file which is ELF and DOES NOT have the initrd and can not be booted:
-rw-r--r-- 1  me users  8814700 Oct 31 14:04 vmlinuz-from-BR2

$ file vmlinuz-from-BR2 
vmlinuz-from-BR2: ELF 32-bit LSB executable, MIPS, MIPS32 version 1 (SYSV),
statically linked, stripped

The reasons I am saying that initrd is not linked in, is because:
a) the vmlinuz image dies very early during the TFTP transfer (packet 8 or 9).
b) because I also tried compiling a vmlinux image+initrd. That one is about
21MB and about 8.8MB stripped and gzipped. I tried booting the gzipped vmlinux
and it works fine. I do not yet know the reason why it is so much bigger than
Broadcom's original vmlinuz image, but I suppose it is because I linked in
various packages to play with - DirectFB, SDL, SDL2, etc...

 = = =

So firstly, it seems that the option 'initial RAM filesystem linked into linux
kernel' from the Filesystem images menu is ignored in the case of vmlinuz.

Secondly, I was expecting a gzipped data (not and ELF binary) when option
'Kernel compression format (gzip compression)' is selected (regardless of
vmlinux/vmlinuz).

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

--- Comment #1 from Alexander Enchevich <a.enchevich@gmail.com> ---
Created attachment 7381
  --> https://bugs.busybox.net/attachment.cgi?id=7381&action=edit
Kernel .config file

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

--- Comment #2 from Alexander Enchevich <a.enchevich@gmail.com> ---
Reading the above perhaps a quick clarification is in order to help understand
why I believe the vmlinuz produced by buildroot is significantly smaller then
it should be (and hence, IMO, is missing the initial ram disk):

Good vmlinuZ (from Broadcom):
compressed:    6 MB
uncompressed: 13 MB


Good vmlinuX (from buildroot):
compressed:    9 MB
uncompressed: 21 MB


BAD vmlinuZ (from buildroot):
compressed:    9 MB (8.8)
uncompressed:  9 MB (8.7)

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

--- Comment #3 from Alexander Enchevich <a.enchevich@gmail.com> ---
Created attachment 7386
  --> https://bugs.busybox.net/attachment.cgi?id=7386&action=edit
Buildroot defconfig

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

--- Comment #4 from Alexander Enchevich <a.enchevich@gmail.com> ---
Created attachment 7391
  --> https://bugs.busybox.net/attachment.cgi?id=7391&action=edit
Kernel's defconfig

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

--- Comment #5 from Alexander Enchevich <a.enchevich@gmail.com> ---
The git repo for Broadcom's stblinux 3.3 is
https://github.com/Broadcom/stblinux-3.3.git. However it can not be used as a
git URL directly because the kernel is not at the top level but dir down. The
version I used is latest at time of filing this bug (tag: stblinux-3.3-4.2).

To make this kernel compile with the standard buildroot gcc compiler and
binutils I made a patch, because there was a problem with binutils > v.2.24.51
not being able to mix hard- and softfloat FPU mode/instructions.

Also the the gzip compression option was ignored, for which there is also
patch.

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

Alexander Enchevich <a.enchevich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |a.enchevich at gmail.com

--- Comment #6 from Alexander Enchevich <a.enchevich@gmail.com> ---
Created attachment 7396
  --> https://bugs.busybox.net/attachment.cgi?id=7396&action=edit
patch kernel to compile with buildroot's gcc 4.8.x

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

--- Comment #7 from Alexander Enchevich <a.enchevich@gmail.com> ---
Created attachment 7401
  --> https://bugs.busybox.net/attachment.cgi?id=7401&action=edit
Enable kernel gzip compression

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

--- Comment #8 from Thomas Petazzoni <thomas.petazzoni@free-electrons.com> ---
Could you reproduce this problem with a MIPS defconfig available in the
upstream Linux kernel?

I personally really don't want to debug stuff deep down in the Broadcom BSP.

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[Buildroot] [Bug 10471] Building a mipsel kernel format vmlinuz (+ gzip + initrd) generates non-compressed, non-bootable image

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10471

Thomas Petazzoni <thomas.petazzoni@free-electrons.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WONTFIX
             Status|NEW                         |RESOLVED

--- Comment #9 from Thomas Petazzoni <thomas.petazzoni@free-electrons.com> ---
The original contributor never came back with a way to reproduce the problem
with a reasonable kernel version (i.e not the Broadcom BSP), so let's mark  the
bug as WONTFIX.

Do not hesitate to reopen with an easier way to reproduce the problem. Thanks!

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