Magic SysRq over telnet
Cute Itanium tricks department:
On the hp Integrity Itanium servers, you can telnet into the management processors and talk to the Linux host's serial console. In particular you can use this to talk to the ELILO boot loader, and to look at oopsies.
One cool thing I recently discovered is that you can send a TELNET BREAK which is translated into a serial break, which has a similar effect to pressing SysRq on a regular keyboard. That is, you can get a list of processes, sync the disks, or unmount the disks for a semi-graceful reboot.
To send a break from the standard Unix telnet client, hit Ctrl+] then type send brk. You need to pause for a second or so after typing this because the break locks out other activity on the serial port.
Debian GNU/Linux testing/unstable kate console
Linux ia64 2.4.22-showmem #29 SMP Wed Oct 29 14:59:35 EST 2003
kate login:
telnet> send break
SysRq : HELP : loglevel0-8 reBoot tErm kIll saK showMem Off showPc
unRaw Sync showTasks Unmount
telnet> send break
pSysRq : Show Regs
Pid: 0, CPU 1, comm: swapper
psr : 0000101008026018 ifs : 8000000000000000 ip :
[<e000000004415440>] Not tainted
ip is at (no symbol)
unat: 0000000000000000 pfs : 000000000000050a rsc : 0000000000000003
rnat: 8000000000000013 bsps: 000000000001003e pr : 80000000ff605935
ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c8a70433f
csd : 0000000000000000 ssd : 0000000000000000
b0 : e0000000044155f0 b6 : e000000004402d60 b7 : e000000004415440
f6 : 1003e2e8ba2e8ba2e8ba3 f7 : 1003e000000000b0b5c99
f8 : 1003e0000000000fd086b f9 : 1003e000000000adf5c99
f10 : 000000000000000000000 f11 : 1003e000000000b0b5c99
r1 : e000000004c6ea80 r2 : 0000000000000000 r3 : 0000000000000000
r8 : 0000000000000000 r9 : e0000040fffa8050 r10 : 0000000000000000
r11 : 0000000000000000 r12 : e0000040fef87e30 r13 : e0000040fef80000
r14 : e0000040fef87dd0 r15 : e0000040fef80028 r16 : 0000000000000000
r17 : 0000000000000000 r18 : e000000004a78688 r19 : e0000040fef80038
r20 : 0000000000000000 r21 : 0000000000000000 r22 : e0000040fef80028
r23 : e000000004415440 r24 : 0000000000000000 r25 : 0000000000000000
r26 : 0000000000000000 r27 : e0000040fef80e90 r28 : 80000000ff606535
r29 : 0000000000000001 r30 : 0000000000000000 r31 : 0000000000000001
posted Wed 29 Oct 2003 in /computers/hardware/rx2600 | link
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