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P4080: How to support 4GB DDR3 in Linux kernel?

Question asked by AMIT SHAH on May 24, 2015
Latest reply on May 29, 2015 by Yiping Wang

Hi All,


I'm working on P4080 based system with Linux running on it. It has 4GB ddr3 memory(2GB per controller).

During boot-up, kernel is crashing if i don't mention the size in bootargs, and kernel is booting-up when i passed only 2GB ddr3 size in u-boot bootargs which actually has 4GB ddr3 memory. I've enabled 4GB(2GB per ddr3 controller) in u-boot with using 36-bit physical addressing.


Also in u-boot bootup , it says 2GB left unmapped, which later on came to know that P4080 platform specific ddr initialization is using max 2GB size.


I've enabled "large physical address support" and SWIOTLB options in kernel also, still giving same error. Device tree file also using 36-bit physical addressing.


Is there anything still we have to enable to use 4GB memory in Linux? Please share your ideas guys..


Kernel crash comes as:



Machine check in kernel mode.

Caused by (from MCSR=8000): Load Error Report

Oops: Machine check, sig: 7 [#1]

SMP NR_CPUS=8 CoreNet Generic

Modules linked in:

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.12.19-rt30-QorIQ-SDK-V1.6+gc29fe1a #23

task: ee084a30 ti: efbae000 task.ti: ee0a2000

NIP: c01ef070 LR: c01ef060 CTR: 00000000

REGS: efbaff10 TRAP: 0204   Not tainted  (3.12.19-rt30-QorIQ-SDK-V1.6+gc29fe1a)

MSR: 00029002 <CE,EE,ME>  CR: 84844e48  XER: 00000000


GPR00: c01ef01c ee0a3c30 ee084a30 f1049040 c0325214 c03b9ec4 ee1d2ba0 00000fe4

GPR08: 38241215 00000000 f104a278 38241215 84844e88 00000000 c00027f0 00000000

GPR16: 00000000 20000000 00000000 c039222c 00500001 ed010d20 00000002 c02a230c

GPR24: c03b1044 c02a21f0 c0389fb8 ee2810c0 00000000 ee1d6400 00000000 f1048000

NIP [c01ef070] n_tty_open+0x70/0x130

LR [c01ef060] n_tty_open+0x60/0x130

Call Trace:

[ee0a3c30] [c01ef01c] n_tty_open+0x1c/0x130 (unreliable)

[ee0a3c50] [c01f3c1c] tty_ldisc_open.isra.6+0x5c/0xa0

[ee0a3c60] [c01f4544] tty_ldisc_setup+0x24/0xc0

[ee0a3c80] [c01eb698] tty_init_dev+0xb8/0x1e0

[ee0a3ca0] [c01ec3b0] tty_open+0x330/0x680

[ee0a3d00] [c00eaedc] chrdev_open+0xbc/0x1c0

[ee0a3d30] [c00e3dc0] do_dentry_open.isra.15+0x190/0x2b0

[ee0a3d50] [c00e3f0c] finish_open+0x2c/0x60

[ee0a3d60] [c00f504c] do_last.isra.47+0x3fc/0xbe0

[ee0a3dd0] [c00f58e4] path_openat+0xb4/0x640

[ee0a3e30] [c00f6cb0] do_filp_open+0x30/0x90

[ee0a3eb0] [c00e52f8] do_sys_open+0x148/0x280

[ee0a3ef0] [c03558fc] kernel_init_freeable+0x160/0x1d0

[ee0a3f20] [c0002808] kernel_init+0x18/0x170

[ee0a3f40] [c000fca4] ret_from_kernel_thread+0x5c/0x64

Instruction dump:

913f0034 388451f8 4be8e5a9 3c80c032 387f2270 7fc5f378 38845214 4be8e595

93fd01a0 3bc00000 93df2244 387f1040 <893f003d> 38800000 93df0004 38a00200

---[ end trace 91dd2f21b34be299 ]---


Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007


Rebooting in 180 seconds.






Amit Shah