Comment 31 for bug 633227

flag@flag-desktop:~$ cat /proc/cmdline
console=ttyO2,115200n8 ro elevator=noop vram=32M mem=460M@0x80000000 mem=512M@0xA0000000 root=UUID=12bb2147-1997-42a8-b7e0-8e44ed0649ef fixrtc

flag@flag-desktop:~$ sudo ./devmem2 0x4A002204
/dev/mem opened.
Memory mapped at address 0x40119000.
Value at address 0x4A002204 (0x40119204): 0x3B95C02F

natty/ti-omap4:

flag@flag-desktop:~$ uname -a
Linux flag-desktop 2.6.38-1207-omap4 #10 SMP PREEMPT Thu Mar 31 18:12:49 CEST 2011 armv7l GNU/Linux

-8+ hours of continuous kernel compilation (rootfs on sd, linux source on nfs) with no ill effects
-strangely memtester doesn't even start:

flag@flag-desktop:~$ sudo memtester -p 0xb0000000 120
memtester version 4.1.3 (32-bit)
Copyright (C) 2010 Charles Cazabon.
Licensed under the GNU General Public License version 2 (only).

pagesize is 4096
pagesizemask is 0xfffff000
want 120MB (125829120 bytes)
failed to mmap /dev/mem for physical memory: Operation not permitted

modifying boot.scr from "mem=512M@0xA0000000" to "mem=256M@0xA0000000" makes memtest work for hours with no problem.

on the other hand, with a maverick/ti-omap4 kernel:

flag@flag-desktop:~$ uname -a
Linux flag-desktop 2.6.35-903-omap4 #22 SMP PREEMPT Thu Mar 31 17:34:59 CEST 2011 armv7l GNU/Linux

flag@flag-desktop:~$ sudo memtester -p 0xb0000000 120
memtester version 4.1.3 (32-bit)
Copyright (C) 2010 Charles Cazabon.
Licensed under the GNU General Public License version 2 (only).

pagesize is 4096
pagesizemask is 0xfffff000
want 120MB (125829120 bytes)
Loop 1:
  Stuck Address : setting 0
Connection to panda closed.

on the serial console:

                                                                               [ 65.264556] Kernel panic - not syncing: Attempted to kill init!
[ 65.270751] [<80046788>] (unwind_backtrace+0x0/0xe4) from [<80546ff4>] (panic+0x58/0xe4)
[ 65.279235] [<80546ff4>] (panic+0x58/0xe4) from [<8007e9d8>] (find_new_reaper+0x6c/0x98)
[ 65.287719] [<8007e9d8>] (find_new_reaper+0x6c/0x98) from [<80080004>] (forget_original_parent+0x28/0x128)
[ 65.297821] [<80080004>] (forget_original_parent+0x28/0x128) from [<80080114>] (exit_notify+0x10/0x134)
[ 65.307617] [<80080114>] (exit_notify+0x10/0x134) from [<800804fc>] (do_exit+0x2c4/0x34c)
[ 65.316192] [<800804fc>] (do_exit+0x2c4/0x34c) from [<80080614>] (do_group_exit+0x90/0xc0)
[ 65.324829] [<80080614>] (do_group_exit+0x90/0xc0) from [<8008f524>] (get_signal_to_deliver+0x2bc/0x2f4)
[ 65.334808] [<8008f524>] (get_signal_to_deliver+0x2bc/0x2f4) from [<80042a3c>] (do_signal+0x50/0x1d4)
[ 65.344512] [<80042a3c>] (do_signal+0x50/0x1d4) from [<80042bd8>] (do_notify_resume+0x18/0x50)
[ 65.353546] [<80042bd8>] (do_notify_resume+0x18/0x50) from [<8003faf0>] (work_pending+0x1c/0x20)
[ 65.362792] CPU0: stopping
[ 65.362823] [<80046788>] (unwind_backtrace+0x0/0xe4) from [<800450bc>] (ipi_cpu_stop+0x30/0x5c)
[ 65.362854] [<800450bc>] (ipi_cpu_stop+0x30/0x5c) from [<8003f268>] (do_IPI+0xc0/0x104)
[ 65.362884] [<8003f268>] (do_IPI+0xc0/0x104) from [<8054a208>] (__irq_svc+0x48/0xe0)
[ 65.362884] Exception stack(0xbecd9ea0 to 0xbecd9ee8)
[ 65.362884] 9ea0: 00000200 80fe4620 00000000 00000aa3 becd9fb0 80000007 bf1ba000 bece1720
[ 65.362915] 9ec0: bf1ba038 00000000 2b9eb004 2b9f4978 00000000 becd9ee8 800f5070 8054c2ac
[ 65.362915] 9ee0: 60000013 ffffffff
[ 65.362945] [<8054a208>] (__irq_svc+0x48/0xe0) from [<8054c2ac>] (do_page_fault+0x118/0x1c4)
[ 65.362945] [<8054c2ac>] (do_page_fault+0x118/0x1c4) from [<8003f350>] (do_PrefetchAbort+0x34/0x98)
[ 65.362976] [<8003f350>] (do_PrefetchAbort+0x34/0x98) from [<8054a6a0>] (ret_from_exception+0x0/0x10)
[ 65.362976] Exception stack(0xbecd9fb0 to 0xbecd9ff8)
[ 65.362976] 9fa0: 2b9d6000 2b9eb005 00015005 2b9f5f28
[ 65.363006] 9fc0: 2ab3bcd0 00000062 7ef1b698 7ef1b828 2ab33de0 00000000 0000004d 2b9f4978
[ 65.363006] 9fe0: 0000045c 7ef1b690 2ab1f97d 2b9eb004 00000030 ffffffff

sometimes it just hangs there (without any panic() message), other it spits out tons of messages about filesystem badness, crashes and later i've to manually fsck -y it, others it just kills memtester and make it impossible to run it again, etcetc.