[Buildroot] [Bug 8271] New: Buildroot wit x86_64 architecture fails to boot on qemu with kernels >=3.10

[Buildroot] [Bug 8271] New: Buildroot wit x86_64 architecture fails to boot on qemu with kernels >=3.10

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8271

           Summary: Buildroot wit x86_64 architecture fails to boot on
                    qemu with kernels >=3.10
           Product: buildroot
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: critical
          Priority: P5
         Component: Other
        AssignedTo: unassigned at buildroot.uclibc.org
        ReportedBy: gleb at pomykalov.ru
                CC: buildroot at uclibc.org
   Estimated Hours: 0.0


Buildroot with x86_64 arch selected and kernels >=3.10 fails to boot on both
qemu and virtualbox.
Here is the kernel panic:
[    0.340000]  [<ffffffff813d207f>] extract_buf+0x8f/0x120
[    0.340000]  [<ffffffff813d06be>] ? account+0x13e/0x180
[    0.340000]  [<ffffffff813d250b>] ? xfer_secondary_pool+0x1b/0x60
[    0.340000]  [<ffffffff813d219c>] extract_entropy+0x8c/0x1c0
[    0.340000]  [<ffffffff8131a149>] ? vsnprintf+0x109/0x580
[    0.340000]  [<ffffffff81f8520a>] ? tc_action_init+0x55/0x55
[    0.340000]  [<ffffffff81325121>] ? bucket_table_alloc+0x111/0x1b0
[    0.340000]  [<ffffffff813d2586>] get_random_bytes+0x36/0x70
[    0.340000]  [<ffffffff81325121>] bucket_table_alloc+0x111/0x1b0
[    0.340000]  [<ffffffff81f8520a>] ? tc_action_init+0x55/0x55
[    0.340000]  [<ffffffff81f8520a>] ? tc_action_init+0x55/0x55
[    0.340000]  [<ffffffff81325467>] rhashtable_init+0x1c7/0x3e0
[    0.340000]  [<ffffffff81f8526b>] netlink_proto_init+0x61/0x15d
[    0.340000]  [<ffffffff810002c4>] do_one_initcall+0x84/0x1b0
[    0.340000]  [<ffffffff81f34fe7>] kernel_init_freeable+0x146/0x1d3
[    0.340000]  [<ffffffff818865d0>] ? rest_init+0x80/0x80
[    0.340000]  [<ffffffff818865d9>] kernel_init+0x9/0xf0
[    0.340000]  [<ffffffff818929d2>] ret_from_fork+0x42/0x70
[    0.340000]  [<ffffffff818865d0>] ? rest_init+0x80/0x80
[    0.340000] Code: 55 8b 0f 44 8b 4f 10 44 8b 57 08 48 89 e5 41 57 41 56 41
55
41 54 89 c8 53 8b 5f 0c c1 c0 05 44 8b 47 04 45 8d a4 01 99 79 82 5a <44> 0f 38
f0 1e 89 d8 44 31 d0 44 89 1a 44 21 c0 41 c1 c8 02 31
[    0.340000] RIP  [<ffffffff8131531b>] sha_transform+0x2b/0x1110
[    0.340000]  RSP <ffff88007d3e7c90>

I've tried different configuration, with various bootloaders, gcc, buildoot
versions. At the same time, i386 architecture works just great.

-- 
Configure bugmail: https://bugs.busybox.net/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.

[Buildroot] [Bug 8271] Buildroot wit x86_64 architecture fails to boot on qemu with kernels >=3.10

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8271

--- Comment #1 from Thomas Petazzoni <thomas.petazzoni@free-electrons.com> 2015-08-10 11:31:25 UTC ---
Could you try:

 1/ make clean
 2/ make qemu_x86_64_defconfig
 3/ make
 4/ Follow the instructions in board/qemu/x86_64/readme.txt

Thanks!

-- 
Configure bugmail: https://bugs.busybox.net/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.

[Buildroot] [Bug 8271] Buildroot wit x86_64 architecture fails to boot on qemu with kernels >=3.10

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8271

--- Comment #2 from Gleb Pomykalov <gleb@pomykalov.ru> 2015-08-10 13:52:25 UTC ---
I have tried more different kernel version, and came to conclusion, that the
first kernel version, where this issue appeared was 3.9. 
I have done bisection of linux kernel. Here is the linux kernel commit that
breaks things:

commit 83a57a4de1a222c351667ef9a0fedaac1295e85b
Author: David Woodhouse <dwmw2@infradead.org>
Date:   Thu Dec 20 01:16:20 2012 +0000

    x86: Enable ARCH_USE_BUILTIN_BSWAP

    With -mmovbe enabled (implicit with -march=atom), this allows the
    compiler to use the movbe instruction. This doesn't have a significant
    effect on code size (unlike on PowerPC), because the movbe instruction
    actually takes as many bytes to encode as a simple mov and a bswap. But
    for Atom in particular I believe it should give a performance win over
    the mov+bswap alternative. That was kind of why movbe was invented in
    the first place, after all...

    I've done basic functionality testing with IPv6 and Legacy IP, but no
    performance testing. The EFI firmware on my test box unfortunately no
    longer starts up.

    Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
    Link:
http://lkml.kernel.org/r/1355966180.18919.102.camel at shinybook.infradead.org
    Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 79795af..3e941aa 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -114,6 +114,7 @@ config X86
        select MODULES_USE_ELF_RELA if X86_64
        select CLONE_BACKWARDS if X86_32
        select GENERIC_SIGALTSTACK
+       select ARCH_USE_BUILTIN_BSWAP

 config INSTRUCTION_DECODER
        def_bool y

Revert this commit on later versions of kernel fix it. It seems, that this
commit enables some functionality for atom processors, which was selected as
arch variant in my case. 

Using your recommendations with "make qemu_x86_64_defconfig" command works as
well. It seems that the reason is in atom arch variant.

-- 
Configure bugmail: https://bugs.busybox.net/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.

[Buildroot] [Bug 8271] Buildroot wit x86_64 architecture fails to boot on qemu with kernels >=3.10

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8271

--- Comment #3 from Gustavo Zacarias <gustavo@zacarias.com.ar> 2015-08-24 21:32:12 UTC ---
Can you provide us with the config files you used?
I tried to reproduce locally by using the qemu_x86_64_defconfig just adjusting
optimization to atom and everything worked fine, on qemu 2.2.0 / ubuntu 15.04
However i do lack an atom, it was runtime-tested on a core m which i'd bet has
all of the atom instructions plus a lot more.

-- 
Configure bugmail: https://bugs.busybox.net/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.

[Buildroot] [Bug 8271] Buildroot wit x86_64 architecture fails to boot on qemu with kernels >=3.10

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8271

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

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

--- Comment #4 from Thomas Petazzoni <thomas.petazzoni@free-electrons.com> 2015-10-14 12:38:18 UTC ---
Did you specify explicitly a CPU model to be emulated by Qemu using the -cpu
option? If you don't, my understanding is that it will emulate a CPU similar to
the host CPU (but I'm not sure about this). In any case, if your Qemu was
emulating something that didn't support the movbe instruction, then it would
break exactly like it did for you. Can you please check your Qemu setup ?

Also, old versions of Qemu were not properly emulating the n270 (which is the
Qemu speak for Atom), and were precisely not emulating the movbe instruction:
https://lists.gnu.org/archive/html/qemu-devel/2013-02/msg01201.html.

So my bet is really an emulation issue on your side. I've looked at the kernel,
and the ARCH_USE_BUILTIN_BSWAP option has not been removed since commit
83a57a4de1a222c351667ef9a0fedaac1295e85b, so I believe that this kernel commit
has since then been widely tested, and that it is correct.

I'll mark the bug as "works for me". Please do not hesitate to re-open with
more details about your Qemu setup (version, and which -cpu option you've used)
if you can still reproduce the problem. Thanks!

-- 
Configure bugmail: https://bugs.busybox.net/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.