yocto1.6 kernel crash after disabling Altivec

[sanojkumar]

Hi All,

I am working on freescales T4240 PPC  board with yocto 1.6 (t4240rdb) branch.

I want to disable the Altivec inorder to relate the performance of CPU in terms of utilization and speed.

By default the kernel is compiled with altivec enabled. When i try to compile the kernel with Altivec disabled

it crashes after root mount (see below logs). We want to write the altivec algorithm for RAID5. It seems we are

not able to disable it for some basic testing.

8021q: 802.1Q VLAN Support v1.8

Key type dns_resolver registered

fsl_dpa_macless: FSL DPAA MACless Ethernet driver ()

fsl_dpa_generic: FSL DPAA Generic Ethernet driver ()

rtc-ds1374 0-0068: setting system clock to 2015-02-09 15:49:14 UTC (1423496954)

md: Skipping autodetection of RAID arrays. (raid=autodetect will force)

RAMDISK: gzip image found at block 0

VFS: Mounted root (ext2 filesystem) on device 1:0.

devtmpfs: mounted

Freeing unused kernel memory: 324K (c0000000009e8000 - c000000000a39000)

init[1]: unhandled signal 4 at f7e5fb04 nip f7e5fb04 lr f7e46b08 code 30001

Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004

CPU: 2 PID: 1 Comm: init Not tainted 3.12.19-rt30-QorIQ-SDK-V1.6+gc29fe1a #12

Call Trace:

[c00000017913b810] [c00000000000732c] .show_stack+0x7c/0x1cc (unreliable)

[c00000017913b8e0] [c000000000740798] .dump_stack+0x84/0xb0

[c00000017913b960] [c00000000073e108] .panic+0xec/0x25c

[c00000017913b9f0] [c00000000004d2a0] .do_exit+0x8f8/0x9d0

[c00000017913bae0] [c00000000004e408] .do_group_exit+0x50/0xe8

[c00000017913bb70] [c00000000005cf10] .get_signal_to_deliver+0x1c8/0x628

[c00000017913bc70] [c0000000000090ec] .do_signal+0x54/0x2b0

[c00000017913bdb0] [c000000000009470] .do_notify_resume+0x64/0x78

[c00000017913be30] [c000000000000b44] .ret_from_except_lite+0x70/0x74

Rebooting in 180 seconds..

Every time i get this crash please help me debugging this.

[scottwood]

If you disable Altivec in the kernel you need to use an RFS that will not use Altivec (not even conditionally based on PVR).

[sanojkumar]

Hi Scott,

Thanks for your reply.

But I couldn't get wherever you are pointing at!!! I did not understand the RFS meaning. Can you please elaborate a little?

[scottwood]

RFS = root filesystem

The kernel panic isn't directly because you disabled Altivec -- it's panicking because init crashed.  Init crashed because it tried to use Altivec on a kernel that doesn't support it.