linux-stable.git/arch/parisc, branch v4.9 Linux kernel stable tree parisc: Fix TLB related boot crash on SMP machines 2016-12-08T20:27:18+00:00 Helge Deller deller@gmx.de 2016-12-08T20:00:46+00:00 24d0492b7d5d321a9c5846c8c974eba9823ffaa0 At bootup we run measurements to calculate the best threshold for when we should be using full TLB flushes instead of just flushing a specific amount of TLB entries. This performance test is run over the kernel text segment. But running this TLB performance test on the kernel text segment turned out to crash some SMP machines when the kernel text pages were mapped as huge pages. To avoid those crashes this patch simply skips this test on some SMP machines and calculates an optimal threshold based on the maximum number of available TLB entries and number of online CPUs. On a technical side, this seems to happen: The TLB measurement code uses flush_tlb_kernel_range() to flush specific TLB entries with a page size of 4k (pdtlb 0(sr1,addr)). On UP systems this purge instruction seems to work without problems even if the pages were mapped as huge pages. But on SMP systems the TLB purge instruction is broadcasted to other CPUs. Those CPUs then crash the machine because the page size is not as expected. C8000 machines with PA8800/PA8900 CPUs were not affected by this problem, because the required cache coherency prohibits to use huge pages at all. Sadly I didn't found any documentation about this behaviour, so this finding is purely based on testing with phyiscal SMP machines (A500-44 and J5000, both were 2-way boxes). Cc: <stable@vger.kernel.org> # v3.18+ Signed-off-by: Helge Deller <deller@gmx.de> 
At bootup we run measurements to calculate the best threshold for when we
should be using full TLB flushes instead of just flushing a specific amount of
TLB entries.  This performance test is run over the kernel text segment.

But running this TLB performance test on the kernel text segment turned out to
crash some SMP machines when the kernel text pages were mapped as huge pages.

To avoid those crashes this patch simply skips this test on some SMP machines
and calculates an optimal threshold based on the maximum number of available
TLB entries and number of online CPUs.

On a technical side, this seems to happen:
The TLB measurement code uses flush_tlb_kernel_range() to flush specific TLB
entries with a page size of 4k (pdtlb 0(sr1,addr)). On UP systems this purge
instruction seems to work without problems even if the pages were mapped as
huge pages.  But on SMP systems the TLB purge instruction is broadcasted to
other CPUs. Those CPUs then crash the machine because the page size is not as
expected.  C8000 machines with PA8800/PA8900 CPUs were not affected by this
problem, because the required cache coherency prohibits to use huge pages at
all.  Sadly I didn't found any documentation about this behaviour, so this
finding is purely based on testing with phyiscal SMP machines (A500-44 and
J5000, both were 2-way boxes).

Cc: <stable@vger.kernel.org> # v3.18+
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Remove unnecessary TLB purges from flush_dcache_page_asm and flush_icache_page_asm 2016-12-07T08:01:21+00:00 John David Anglin dave.anglin@bell.net 2016-12-07T03:02:01+00:00 febe42964fe182281859b3d43d844bb25ca49367 We have four routines in pacache.S that use temporary alias pages: copy_user_page_asm(), clear_user_page_asm(), flush_dcache_page_asm() and flush_icache_page_asm(). copy_user_page_asm() and clear_user_page_asm() don't purge the TLB entry used for the operation. flush_dcache_page_asm() and flush_icache_page_asm do purge the entry. Presumably, this was thought to optimize TLB use. However, the operation is quite heavy weight on PA 1.X processors as we need to take the TLB lock and a TLB broadcast is sent to all processors. This patch removes the purges from flush_dcache_page_asm() and flush_icache_page_asm. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: <stable@vger.kernel.org> # v3.16+ Signed-off-by: Helge Deller <deller@gmx.de> 
We have four routines in pacache.S that use temporary alias pages:
copy_user_page_asm(), clear_user_page_asm(), flush_dcache_page_asm() and
flush_icache_page_asm().  copy_user_page_asm() and clear_user_page_asm()
don't purge the TLB entry used for the operation.
flush_dcache_page_asm() and flush_icache_page_asm do purge the entry.

Presumably, this was thought to optimize TLB use.  However, the
operation is quite heavy weight on PA 1.X processors as we need to take
the TLB lock and a TLB broadcast is sent to all processors.

This patch removes the purges from flush_dcache_page_asm() and
flush_icache_page_asm.

Signed-off-by: John David Anglin  <dave.anglin@bell.net>
Cc: <stable@vger.kernel.org> # v3.16+
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Purge TLB before setting PTE 2016-12-07T07:56:40+00:00 John David Anglin dave.anglin@bell.net 2016-12-07T02:47:04+00:00 c78e710c1c9fbeff43dddc0aa3d0ff458e70b0cc The attached change interchanges the order of purging the TLB and setting the corresponding page table entry. TLB purges are strongly ordered. It occurred to me one night that setting the PTE first might have subtle ordering issues on SMP machines and cause random memory corruption. A TLB lock guards the insertion of user TLB entries. So after the TLB is purged, a new entry can't be inserted until the lock is released. This ensures that the new PTE value is used when the lock is released. Since making this change, no random segmentation faults have been observed on the Debian hppa buildd servers. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: <stable@vger.kernel.org> # v3.16+ Signed-off-by: Helge Deller <deller@gmx.de> 
The attached change interchanges the order of purging the TLB and
setting the corresponding page table entry.  TLB purges are strongly
ordered.  It occurred to me one night that setting the PTE first might
have subtle ordering issues on SMP machines and cause random memory
corruption.

A TLB lock guards the insertion of user TLB entries.  So after the TLB
is purged, a new entry can't be inserted until the lock is released.
This ensures that the new PTE value is used when the lock is released.

Since making this change, no random segmentation faults have been
observed on the Debian hppa buildd servers.

Signed-off-by: John David Anglin  <dave.anglin@bell.net>
Cc: <stable@vger.kernel.org> # v3.16+
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Also flush data TLB in flush_icache_page_asm 2016-11-25T11:32:01+00:00 John David Anglin dave.anglin@bell.net 2016-11-25T01:18:14+00:00 5035b230e7b67ac12691ed3b5495bbb617027b68 This is the second issue I noticed in reviewing the parisc TLB code. The fic instruction may use either the instruction or data TLB in flushing the instruction cache. Thus, on machines with a split TLB, we should also flush the data TLB after setting up the temporary alias registers. Although this has no functional impact, I changed the pdtlb and pitlb instructions to consistently use the index register %r0. These instructions do not support integer displacements. Tested on rp3440 and c8000. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: <stable@vger.kernel.org> # v3.16+ Signed-off-by: Helge Deller <deller@gmx.de> 
This is the second issue I noticed in reviewing the parisc TLB code.

The fic instruction may use either the instruction or data TLB in
flushing the instruction cache.  Thus, on machines with a split TLB, we
should also flush the data TLB after setting up the temporary alias
registers.

Although this has no functional impact, I changed the pdtlb and pitlb
instructions to consistently use the index register %r0.  These
instructions do not support integer displacements.

Tested on rp3440 and c8000.

Signed-off-by: John David Anglin  <dave.anglin@bell.net>
Cc: <stable@vger.kernel.org> # v3.16+
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Fix race in pci-dma.c 2016-11-25T11:31:59+00:00 John David Anglin dave.anglin@bell.net 2016-11-25T01:06:32+00:00 c0452fb9fb8f49c7d68ab9fa0ad092016be7b45f We are still troubled by occasional random segmentation faults and memory memory corruption on SMP machines. The causes quite a few package builds to fail on the Debian buildd machines for parisc. When gcc-6 failed to build three times in a row, I looked again at the TLB related code. I found a couple of issues. This is the first. In general, we need to ensure page table updates and corresponding TLB purges are atomic. The attached patch fixes an instance in pci-dma.c where the page table update was not guarded by the TLB lock. Tested on rp3440 and c8000. So far, no further random segmentation faults have been observed. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: <stable@vger.kernel.org> # v3.16+ Signed-off-by: Helge Deller <deller@gmx.de> 
We are still troubled by occasional random segmentation faults and
memory memory corruption on SMP machines.  The causes quite a few
package builds to fail on the Debian buildd machines for parisc.  When
gcc-6 failed to build three times in a row, I looked again at the TLB
related code.  I found a couple of issues.  This is the first.

In general, we need to ensure page table updates and corresponding TLB
purges are atomic.  The attached patch fixes an instance in pci-dma.c
where the page table update was not guarded by the TLB lock.

Tested on rp3440 and c8000.  So far, no further random segmentation
faults have been observed.

Signed-off-by: John David Anglin  <dave.anglin@bell.net>
Cc: <stable@vger.kernel.org> # v3.16+
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Switch to generic sched_clock implementation 2016-11-25T11:31:58+00:00 Helge Deller deller@gmx.de 2016-11-22T17:08:30+00:00 43b1f6abd59063a088416a0df042b36450f91f75 Drop the open-coded sched_clock() function and replace it by the provided GENERIC_SCHED_CLOCK implementation. We have seen quite some hung tasks in the past, which seem to be fixed by this patch. Signed-off-by: Helge Deller <deller@gmx.de> Cc: <stable@vger.kernel.org> # v4.7+ Signed-off-by: Helge Deller <deller@gmx.de> 
Drop the open-coded sched_clock() function and replace it by the provided
GENERIC_SCHED_CLOCK implementation.  We have seen quite some hung tasks in the
past, which seem to be fixed by this patch.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v4.7+
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Fix races in parisc_setup_cache_timing() 2016-11-25T11:31:57+00:00 John David Anglin dave.anglin@bell.net 2016-11-21T02:12:36+00:00 741dc7bf1c7c7d93b853bb55efe77baa27e1b0a9 Helge reported to me the following startup crash: [ 0.000000] Linux version 4.8.0-1-parisc64-smp (debian-kernel@lists.debian.org) (gcc version 5.4.1 20161019 (GCC) ) #1 SMP Debian 4.8.7-1 (2016-11-13) [ 0.000000] The 64-bit Kernel has started... [ 0.000000] Kernel default page size is 4 KB. Huge pages enabled with 1 MB physical and 2 MB virtual size. [ 0.000000] Determining PDC firmware type: System Map. [ 0.000000] model 9000/785/J5000 [ 0.000000] Total Memory: 2048 MB [ 0.000000] Memory: 2018528K/2097152K available (9272K kernel code, 3053K rwdata, 1319K rodata, 1024K init, 840K bss, 78624K reserved, 0K cma-reserved) [ 0.000000] virtual kernel memory layout: [ 0.000000] vmalloc : 0x0000000000008000 - 0x000000003f000000 (1007 MB) [ 0.000000] memory : 0x0000000040000000 - 0x00000000c0000000 (2048 MB) [ 0.000000] .init : 0x0000000040100000 - 0x0000000040200000 (1024 kB) [ 0.000000] .data : 0x0000000040b0e000 - 0x0000000040f533e0 (4372 kB) [ 0.000000] .text : 0x0000000040200000 - 0x0000000040b0e000 (9272 kB) [ 0.768910] Brought up 1 CPUs [ 0.992465] NET: Registered protocol family 16 [ 2.429981] Releasing cpu 1 now, hpa=fffffffffffa2000 [ 2.635751] CPU(s): 2 out of 2 PA8500 (PCX-W) at 440.000000 MHz online [ 2.726692] Setting cache flush threshold to 1024 kB [ 2.729932] Not-handled unaligned insn 0x43ffff80 [ 2.798114] Setting TLB flush threshold to 140 kB [ 2.928039] Unaligned handler failed, ret = -1 [ 3.000419] _______________________________ [ 3.000419] < Your System ate a SPARC! Gah! > [ 3.000419] ------------------------------- [ 3.000419] \ ^__^ [ 3.000419] (__)\ )\/\ [ 3.000419] U ||----w | [ 3.000419] || || [ 9.340055] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-1-parisc64-smp #1 Debian 4.8.7-1 [ 9.448082] task: 00000000bfd48060 task.stack: 00000000bfd50000 [ 9.528040] [ 10.760029] IASQ: 0000000000000000 0000000000000000 IAOQ: 000000004025d154 000000004025d158 [ 10.868052] IIR: 43ffff80 ISR: 0000000000340000 IOR: 000001ff54150960 [ 10.960029] CPU: 1 CR30: 00000000bfd50000 CR31: 0000000011111111 [ 11.052057] ORIG_R28: 000000004021e3b4 [ 11.100045] IAOQ[0]: irq_exit+0x94/0x120 [ 11.152062] IAOQ[1]: irq_exit+0x98/0x120 [ 11.208031] RP(r2): irq_exit+0xb8/0x120 [ 11.256074] Backtrace: [ 11.288067] [<00000000402cd944>] cpu_startup_entry+0x1e4/0x598 [ 11.368058] [<0000000040109528>] smp_callin+0x2c0/0x2f0 [ 11.436308] [<00000000402b53fc>] update_curr+0x18c/0x2d0 [ 11.508055] [<00000000402b73b8>] dequeue_entity+0x2c0/0x1030 [ 11.584040] [<00000000402b3cc0>] set_next_entity+0x80/0xd30 [ 11.660069] [<00000000402c1594>] pick_next_task_fair+0x614/0x720 [ 11.740085] [<000000004020dd34>] __schedule+0x394/0xa60 [ 11.808054] [<000000004020e488>] schedule+0x88/0x118 [ 11.876039] [<0000000040283d3c>] rescuer_thread+0x4d4/0x5b0 [ 11.948090] [<000000004028fc4c>] kthread+0x1ec/0x248 [ 12.016053] [<0000000040205020>] end_fault_vector+0x20/0xc0 [ 12.092239] [<00000000402050c0>] _switch_to_ret+0x0/0xf40 [ 12.164044] [ 12.184036] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-1-parisc64-smp #1 Debian 4.8.7-1 [ 12.244040] Backtrace: [ 12.244040] [<000000004021c480>] show_stack+0x68/0x80 [ 12.244040] [<00000000406f332c>] dump_stack+0xec/0x168 [ 12.244040] [<000000004021c74c>] die_if_kernel+0x25c/0x430 [ 12.244040] [<000000004022d320>] handle_unaligned+0xb48/0xb50 [ 12.244040] [ 12.632066] ---[ end trace 9ca05a7215c7bbb2 ]--- [ 12.692036] Kernel panic - not syncing: Attempted to kill the idle task! We have the insn 0x43ffff80 in IIR but from IAOQ we should have: 4025d150: 0f f3 20 df ldd,s r19(r31),r31 4025d154: 0f 9f 00 9c ldw r31(ret0),ret0 4025d158: bf 80 20 58 cmpb,*<> r0,ret0,4025d18c <irq_exit+0xcc> Cpu0 has just completed running parisc_setup_cache_timing: [ 2.429981] Releasing cpu 1 now, hpa=fffffffffffa2000 [ 2.635751] CPU(s): 2 out of 2 PA8500 (PCX-W) at 440.000000 MHz online [ 2.726692] Setting cache flush threshold to 1024 kB [ 2.729932] Not-handled unaligned insn 0x43ffff80 [ 2.798114] Setting TLB flush threshold to 140 kB [ 2.928039] Unaligned handler failed, ret = -1 From the backtrace, cpu1 is in smp_callin: void __init smp_callin(void) { int slave_id = cpu_now_booting; smp_cpu_init(slave_id); preempt_disable(); flush_cache_all_local(); /* start with known state */ flush_tlb_all_local(NULL); local_irq_enable(); /* Interrupts have been off until now */ cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); So, it has just flushed its caches and the TLB. It would seem either the flushes in parisc_setup_cache_timing or smp_callin have corrupted kernel memory. The attached patch reworks parisc_setup_cache_timing to remove the races in setting the cache and TLB flush thresholds. It also corrects the number of bytes flushed in the TLB calculation. The patch flushes the cache and TLB on cpu0 before starting the secondary processors so that they are started from a known state. Tested with a few reboots on c8000. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: <stable@vger.kernel.org> # v3.18+ Signed-off-by: Helge Deller <deller@gmx.de> 
Helge reported to me the following startup crash:

[    0.000000] Linux version 4.8.0-1-parisc64-smp (debian-kernel@lists.debian.org) (gcc version 5.4.1 20161019 (GCC) ) #1 SMP Debian 4.8.7-1 (2016-11-13)
[    0.000000] The 64-bit Kernel has started...
[    0.000000] Kernel default page size is 4 KB. Huge pages enabled with 1 MB physical and 2 MB virtual size.
[    0.000000] Determining PDC firmware type: System Map.
[    0.000000] model 9000/785/J5000
[    0.000000] Total Memory: 2048 MB
[    0.000000] Memory: 2018528K/2097152K available (9272K kernel code, 3053K rwdata, 1319K rodata, 1024K init, 840K bss, 78624K reserved, 0K cma-reserved)
[    0.000000] virtual kernel memory layout:
[    0.000000]     vmalloc : 0x0000000000008000 - 0x000000003f000000   (1007 MB)
[    0.000000]     memory  : 0x0000000040000000 - 0x00000000c0000000   (2048 MB)
[    0.000000]       .init : 0x0000000040100000 - 0x0000000040200000   (1024 kB)
[    0.000000]       .data : 0x0000000040b0e000 - 0x0000000040f533e0   (4372 kB)
[    0.000000]       .text : 0x0000000040200000 - 0x0000000040b0e000   (9272 kB)
[    0.768910] Brought up 1 CPUs
[    0.992465] NET: Registered protocol family 16
[    2.429981] Releasing cpu 1 now, hpa=fffffffffffa2000
[    2.635751] CPU(s): 2 out of 2 PA8500 (PCX-W) at 440.000000 MHz online
[    2.726692] Setting cache flush threshold to 1024 kB
[    2.729932] Not-handled unaligned insn 0x43ffff80
[    2.798114] Setting TLB flush threshold to 140 kB
[    2.928039] Unaligned handler failed, ret = -1
[    3.000419]       _______________________________
[    3.000419]      < Your System ate a SPARC! Gah! >
[    3.000419]       -------------------------------
[    3.000419]              \   ^__^
[    3.000419]                  (__)\       )\/\
[    3.000419]                   U  ||----w |
[    3.000419]                      ||     ||
[    9.340055] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-1-parisc64-smp #1 Debian 4.8.7-1
[    9.448082] task: 00000000bfd48060 task.stack: 00000000bfd50000
[    9.528040]
[   10.760029] IASQ: 0000000000000000 0000000000000000 IAOQ: 000000004025d154 000000004025d158
[   10.868052]  IIR: 43ffff80    ISR: 0000000000340000  IOR: 000001ff54150960
[   10.960029]  CPU:        1   CR30: 00000000bfd50000 CR31: 0000000011111111
[   11.052057]  ORIG_R28: 000000004021e3b4
[   11.100045]  IAOQ[0]: irq_exit+0x94/0x120
[   11.152062]  IAOQ[1]: irq_exit+0x98/0x120
[   11.208031]  RP(r2): irq_exit+0xb8/0x120
[   11.256074] Backtrace:
[   11.288067]  [<00000000402cd944>] cpu_startup_entry+0x1e4/0x598
[   11.368058]  [<0000000040109528>] smp_callin+0x2c0/0x2f0
[   11.436308]  [<00000000402b53fc>] update_curr+0x18c/0x2d0
[   11.508055]  [<00000000402b73b8>] dequeue_entity+0x2c0/0x1030
[   11.584040]  [<00000000402b3cc0>] set_next_entity+0x80/0xd30
[   11.660069]  [<00000000402c1594>] pick_next_task_fair+0x614/0x720
[   11.740085]  [<000000004020dd34>] __schedule+0x394/0xa60
[   11.808054]  [<000000004020e488>] schedule+0x88/0x118
[   11.876039]  [<0000000040283d3c>] rescuer_thread+0x4d4/0x5b0
[   11.948090]  [<000000004028fc4c>] kthread+0x1ec/0x248
[   12.016053]  [<0000000040205020>] end_fault_vector+0x20/0xc0
[   12.092239]  [<00000000402050c0>] _switch_to_ret+0x0/0xf40
[   12.164044]
[   12.184036] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-1-parisc64-smp #1 Debian 4.8.7-1
[   12.244040] Backtrace:
[   12.244040]  [<000000004021c480>] show_stack+0x68/0x80
[   12.244040]  [<00000000406f332c>] dump_stack+0xec/0x168
[   12.244040]  [<000000004021c74c>] die_if_kernel+0x25c/0x430
[   12.244040]  [<000000004022d320>] handle_unaligned+0xb48/0xb50
[   12.244040]
[   12.632066] ---[ end trace 9ca05a7215c7bbb2 ]---
[   12.692036] Kernel panic - not syncing: Attempted to kill the idle task!

We have the insn 0x43ffff80 in IIR but from IAOQ we should have:
   4025d150:   0f f3 20 df     ldd,s r19(r31),r31
   4025d154:   0f 9f 00 9c     ldw r31(ret0),ret0
   4025d158:   bf 80 20 58     cmpb,*<> r0,ret0,4025d18c <irq_exit+0xcc>

Cpu0 has just completed running parisc_setup_cache_timing:

[    2.429981] Releasing cpu 1 now, hpa=fffffffffffa2000
[    2.635751] CPU(s): 2 out of 2 PA8500 (PCX-W) at 440.000000 MHz online
[    2.726692] Setting cache flush threshold to 1024 kB
[    2.729932] Not-handled unaligned insn 0x43ffff80
[    2.798114] Setting TLB flush threshold to 140 kB
[    2.928039] Unaligned handler failed, ret = -1

From the backtrace, cpu1 is in smp_callin:

void __init smp_callin(void)
{
       int slave_id = cpu_now_booting;

       smp_cpu_init(slave_id);
       preempt_disable();

       flush_cache_all_local(); /* start with known state */
       flush_tlb_all_local(NULL);

       local_irq_enable();  /* Interrupts have been off until now */

       cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);

So, it has just flushed its caches and the TLB. It would seem either the
flushes in parisc_setup_cache_timing or smp_callin have corrupted kernel
memory.

The attached patch reworks parisc_setup_cache_timing to remove the races
in setting the cache and TLB flush thresholds. It also corrects the
number of bytes flushed in the TLB calculation.

The patch flushes the cache and TLB on cpu0 before starting the
secondary processors so that they are started from a known state.

Tested with a few reboots on c8000.

Signed-off-by: John David Anglin  <dave.anglin@bell.net>
Cc: <stable@vger.kernel.org> # v3.18+
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Fix printk continuations in system detection 2016-11-22T17:09:33+00:00 Helge Deller deller@gmx.de 2016-11-17T20:13:56+00:00 4345a64ac931a8dc499f1fc69880952412f36c3e Signed-off-by: Helge Deller <deller@gmx.de> 
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Ignore the pkey system calls for now 2016-11-02T22:07:14+00:00 Helge Deller deller@gmx.de 2016-10-29T21:47:57+00:00 18088db042dd9ae25e8a1e069eb3a16db601ef8a Signed-off-by: Helge Deller <deller@gmx.de> 
Signed-off-by: Helge Deller <deller@gmx.de>
parisc: Use LINUX_GATEWAY_ADDR define instead of hardcoded value 2016-11-02T22:06:38+00:00 Helge Deller deller@gmx.de 2016-10-29T21:52:43+00:00 6a6e2a14bbc06a627acc71108808fdc866078db4 LINUX_GATEWAY_ADDR is defined in unistd.h. Let's use it. Signed-off-by: Helge Deller <deller@gmx.de> 
LINUX_GATEWAY_ADDR is defined in unistd.h. Let's use it.

Signed-off-by: Helge Deller <deller@gmx.de>