SIGNAL 11 WHILE COMPILING THE KERNEL

SIGNAL 11 WHILE COMPILING THE KERNEL

This FAQ describes what the possible causes are for an effect that
bothers lots of people lately. Namely that a linux(*)-kernel (or any
other large package for that matter) compile crashes with a "signal
11". The cause can be software or (most likely) hardware. Read on to
find out more.
(*) Of course nothing is Linux specific. If your hardware is flaky,
Linux, Windows 3.1, FreeBSD, Windows NT and NextStep will all crash.

If all is ok, this is now part of the Mini-Howto collection for Linux.
If you're interested, the Web version of this document is now (june
'96) accessed about 300 times per week. (a growth of a factor of three
in 3 months)
If you are not reading this at http://www.bitwizard.nl/sig11/, that's
where you can find the most recent version.
Email me at [email protected] if you find any spelling errors,
worthwhile additions or with an "it also happened to me" story. (Note
that I reject some suggested additions on my belief that it is
technical nonsense).
_________________________________________________________________

The Sig11 FAQ

QUESTION

My kernel compile crashes with

gcc: Internal compiler error: program cc1 got fatal signal 11

What is wrong with the compiler? Which version of the compiler do I
need? Is there something wrong with the kernel?

ANSWER

Most likely there is nothing wrong with your installation, your
compiler or kernel. It very likely has something to do with your
hardware. There are a variety of subsystems that can be wrong, and
there is a variety of ways to fix it. Read on, and you'll find out
more.
_________________________________________________________________

QUESTION

Ok it may not be the software, How do I know for sure?

ANSWER

First lets make sure it is the hardware that is causing your trouble.
When the "make" stops, simply type "make" again. If it compiles a few
more files before stopping, it must be hardware that is causing you
troubles. If it immediately stops again (i.e. scans a few directories
with "nothing to be done for xxxx" before bombing at exactly the same
place), try

dd if=/dev/hda of=/dev/null bs=1024k count=16

Change "hda" to "sda" if you have a SCSI disk. Change the count=16 to
the number of megabytes of main memory that you have. This will cause
the first 16Mb of your harddisk to be read from disk, forcing the C
source files and the gcc binary to be reread from disk the next time
you run it. Now type make again. If it still stops in the same place
I'm starting to wonder if you're reading the right FAQ, as it is
starting to look like a software problem after all.... Take a peek at
the "what are the other possibilities" question..... If without this
"dd" command the compiler keeps on stopping at the same place, but
moves to another place after you use the "dd" you definitely have a
disk->ram transfer problem.

QUESTION

What does it really mean?

ANSWER

Well, the compiler accessed memory outside its memory range. If this
happens on working hardware it's a programming error inside the
compiler. That's why it says "internal compiler error". However when
the hardware occasionally flips a bit, gcc uses so many pointers, that
it is likely to end up accessing something outside of its addressing
range. (random addresses are mostly outside your addressing range, as
not very many people have a significant part of 4G as mainmemory...
:-)
_________________________________________________________________

QUESTION

Ok. I may have a hardware problem what is it?

ANSWER

If it happens to be the hardware it can be:
* Main memory. Your main memory might be getting an occasional bit
wrong. If this happens on the "writes", you won't see any parity
errors. There are several ways to fix it:
+ The memory speed might be too slow. Increase the number of
wait states in the BIOS.
This could be caused by the AMIBIOSs autoconfig option: it
may only know about 486s running upto 80 MHz, whereas you
currently buy 100 MHz versions. -- Pat V.
+ The memory speed might be too slow. Get faster DRAM SIMMs.
For example current ASUS motherboards require 60 ns DRAM if
you have a 100, or 133 MHz processor (Take a look in your
motherboard's manual). I've heard reports that 70 ns also
works, reliability problems like random sig11's belong to the
possibilities.... (I wouldn't take the risk) -- Andrew
Eskilsson ([email protected])
+ There is a bad chip on one of the SIMMs. If you own more than
1 bank of memory you might be able to pull SIMMs and see if
the problem goes away. Be careful for STATIC!!!
+ We handled a hard one here the last week. It turned out that
ALL 4 16Mb SIMMs were broken in that they dropped a bit
around once per hour. This was sufficient to crash the
machine in about a day, or crash a kernel compile in about an
hour. A new set of SIMMs works perfectly. It took a long
while to diagnose this one, because all 4 of the SIMMs were
affected equally, so leaving half of the memory out didn't
change things.
Mark Kettner ([email protected]) reports that his
system was capable of running my memory test for 2300 times
faultlessly, but then detected around 10 errors. It then
continued detecting no faults for a few hundred runs
again..... In his case running kernel compiles was a much
more efficient way of detecting the health of the system (in
the most stable configuration the system could compile around
14 kernels before going bzurk). His solution was to "trade
in" the old memory for a so called "memory upgrade". The
shopkeeper then "tests" in their memory tester, which OKs the
memory. he then got a good discount on the new memory :-).
+ It seems that some 30-72 pin converters can cause memory
errors. (It hasn't been proven whether the 4 SIMMS in the
converter had gone bad, or if the SIMM converter was at
fault. The SIMMS had been functioning perfectly for years
before they were moved into the converter....) -- Naresh
Sharma ([email protected]). Paul Gortmaker
([email protected]) adds that the SIMM converters
should have at least 4 bypass capacitors to keep the power
supply of the SIMMs clean.
+ If the refresh of the DRAM isn't functioning properly, the
DRAMs will slowly lose their information. Some (486)
motherboards stop refreshing correctly when you turn on
"hidden refresh". There seems to be a program called "dram"
around that can also mess up your refresh to cause sig11
problems. -- Hank Barta ([email protected]), Ron Tapia
([email protected])
+ The number of waitstates could be too low. Increase the
number of waiststates in the BIOS for a fix. The Intel
Endeavour board doesn't allow you to increase the memory
waitstates. This can supposedly be fixed by flashing a MR
BIOS into the motherboard. -- David Halls
([email protected])
* Cache memory. Your cache memory might be getting an occasional bit
wrong. Caches are usually not equipped with parity. You can
diagnose that this is the case by turning off the cache in the
BIOS. If the problem goes away it is probably the cache. There are
several ways to fix it:
+ The cache memory speed might be too slow. Increase the number
of wait states in the BIOS.
+ The cache memory speed might be too slow. Get faster SRAM
chips.
+ There is a bad chip in your cache. It is unlikely that you
can swap chips as easily as with SIMMs. Be careful for
STATIC!!! -- Joseph Barone ([email protected])
+ The cache might be set to "write back" while there is a bug
in the write back implementation of your chipset. The
motherboard where this happened was a "MV020 486VL3H" (with
20M RAM) -- Scott Brumbaugh ([email protected])
(Mail address doesn't work. Scott: Get back at me with a
valid return address)
+ The motherboard may require a jumper to switch between Cache
On A Stick and the old-fashioned dip chip cache. (JP16 on Rev
2.4 ASUS motherboards)
* Disk transfers. A block coming from disk might incur an occasional
bit error.
+ If you have this problem, you are most likely to have to do
the "dd" command to "move" the problem from one place to the
next....
+ Some IDE harddisks cannot handle the "irq_unmasking" option.
This may only show under load. And it could show as a sig11.
+ Do you have a kalok 31xx? Throw it in the garbage. (or sell
it to a DOS user)
+ SCSI? Termination? A short bus might still work (unreliably
that is) with bad termination. A long bus might get errors
anyway. Can you turn on parity on the host and the DISK?
* Overclocking. Some vendors (or private people) think it is
possible to overclock some CPUs. Some of them may work others
don't. You might want to try turning off turbo (note that most
pentium motherboards no longer support a non-turbo mode) and see
if the problem goes away. Check the speed of your CPU compared
(printed on it, carefully remove the fan if necessary) with what
the motherboard jumpers or BIOS settings say.... It seems that
even Intel may make mistakes in this area. I now have a reliable
report that an official 120MHz pentium would Sig11 at 120, but not
at 100MHz. As the motherboard is only stressed HARDER for a 100
MHz processor, I think it is unlikely that this has anything to do
with the motherboard. Moreover a new 120MHz processor is now
functioning correctly. -- Samuel Ramac ([email protected]).
* CPU temperature. A high speed processor might overheat without the
correct heat sink. This can also be caused by a failing fan. (My
personal '486 has a fan that takes a few minutes to get up to
speed. It probably will never really FAIL because it's now
decommisioned :-). The CPU can become erratic if "pushed" by
compiling a kernel. This problem becomes worse if you disable
"HALT" on the LILO command line. Linux tries to power-down the CPU
by executing the "halt" instruction when the system is idle. This
preserves power, and therefore the CPU temperature drops when the
system is idle. You therefore might not notice this problem when
simply editing, and it might only surface after hours of CPU
intensive jobs when the ambient temp is high. If you have a
Pentium with Fdiv bug, it is advisable to trade it in at Intel.
They will send you a new one that preconfigured with an official
Intel-approved FAN. Also note that most normal glues are very bad
thermal conductors. There is special thermal glue available that
should be used when a fan needs to be glued to a CPU. -- Arno
Griffioen ([email protected]), -- W. Paul Mills ([email protected]) --
Alan Wind ([email protected])

Intel says that the allowable temperature ranges for the outside
of your CPU is:
0 to +85 C: Intel486 SX, Intel486 DX, IntelDX2, IntelDX4 processor
0 to +95 C: IntelDX2, IntelDX4 OverDrive. processors
0 to +80 C: 60 MHz Pentium. processor
0 to +70 C: 66 to 166 MHz Pentium processor
For information on how to measure this and some confirmation of
what I say here, see:
http://pentium.intel.com/procs/support/faqs/iarcfaq.htm
(Especially questions Q6, Q7 and Q13)
* CPU voltage. Some motherboards allow you to select the CPU
voltage. Some motherboards badly document the jumper settings that
manage this. It seems that a 5V processor might still work most of
the time at 3.3 volts..... -- Karl Heyes ([email protected])
* RAM voltage. It seems that vendors are preparing for 3.3V RAM now.
Most memory is still 5V. (but be careful.... 3.3v RAM will break
at 5V.....)
* Local bus overloading. At 25 MHz you're allowed to have 3
VesaLocalBus cards, At 33MHz only two, at 40MHz only one and guess
what at 50MHz NONE! Some systems start acting flaky when you
overload the VLB. Even when your VLB isn't overloaded (over the
limits stated above), the system may loose a few nanoseconds of
margin by adding an extra VLB card, so you might need to add a
cache wait state or something after you've added a new VLB
card.... -- Richard Postgate ([email protected])
* Power management. Some laptops (and nowadays also "green" pc's)
have power management features. These might interfere with Linux.
One feature might save a memory image to HD and restore the RAM
when you press a key. This sounds like fun, but Linux device
drivers don't expect that the hardware has been turned off between
two acesses. Some may recover, but others not. Try turning it off,
or enabeling "APM support" in your kernel. -- Elizabeth Ayer
([email protected])
* The CPU itself. Several people are reporting that they have found
nothing to blame excpet the CPU. This could also have been an
incompatibility between the CPU and the motherboard. A wave of
reports concerning Intel CPUs has passed (Feb '97). A new wave of
reports is coming in that are blaiming Cyrix/IBM 6x86 CPUs.
Although it could indeed be the CPU, it could also be that your
motherboard is incompatible with your CPU. At least I've seen a
motherboard manual mention that it isn't compatible with older
6x86's. My own experience is that these devices aren't bad at all,
and on a kernel compile I benchmarked a P166+ to be equivalent
with a P155 (1.3 times faster than a P120).

_________________________________________________________________

QUESTION

RAM timing problems? I fiddled with the bios settings more than a
month ago. I've compiled numerous kernels in the mean time and nothing
went wrong. It can't be the RAM timing. Right?

ANSWER

Wrong. Do you think that the RAM manufacturers have a machine that
makes 60ns RAMs and another one that makes 70ns RAMs? Off course not!
They make a bunch, and then test them. Some meet the specs for 60 ns,
others don't. Those might be 61 ns if the manufacturer would have to
put a number to it. In that case it is quite likely that it works in
your computer when for example the temperature is below 40 degrees
centigrade (chips become slower when the temp rises. That's why some
supercomputers need so much cooling).

However "the coming of summer" or a long compile job may push the
temperature inside your computer over the "limit". -- Philippe Troin
([email protected])
_________________________________________________________________

QUESTION

Memory problems? My BIOS tests my memory and tells me its ok. I have
this fancy DOS program that tells me my memory is OK. Can't be memory
right?

ANSWER

Wrong. The memory test in the BIOS is utterly useless. It may even
occasionally OK more memory than really is available, let alone test
whether it is good or not.
A friend of mine used to have a 640k PC which had a single 64kbit chip
instead of a 256kbit chip in the second 256k bank. This means that he
effectively had 320k working memory. Sometimes the BIOS would test
384k as "OK". Anyway, only certain applications would fail. It was
very hard to diagnose the actual problem....
Most memory problems only occur under special circumstances. Those
circumstances are hardly ever known. gcc Seems to exercise them. Some
memory tests, especially BIOS memory tests, don't. I'm working on
creating a floppy with a linux kernel and a good memory tester on it.
Bug me about it again......
The floppy is not ready yet, but if you have a working Linux system
you could try my memtesting program. It is available from
http://www.bitwizard.nl/sig11/memtest.tar.gz (binary) and from
http://www.bitwizard.nl/sig11/memtest.tgz.uue (uuencoded tarred
gzipped). I'm working on something even better, but you will have to
wait for that.....
_________________________________________________________________

QUESTION

Does it only happen when I compile a kernel?

ANSWER

Nope. There is no way your hardware can know that you are compiling a
kernel. It just so happens that a kernel compile is very tough on your
hardware, so it just happens a lot when you are compiling a kernel.
* People have seen "random" crashes for example while installing
using the slackware installation script.... -- [email protected]
* Others get "general protection errors" from the kernel (with the
crashdump). These are usually in /var/adm/messages. --
[email protected]

_________________________________________________________________

QUESTION

Nothing crashes on NT, Windows 95, OS/2 or DOS. It must be something
Linux specific.

ANSWER

First of all, Linux stresses your hardware more than all of the above.
Some OSes like the Microsoft ones named above crash in unpredictable
ways anyway. Nobody is going to call Microsoft and say "hey, my
windows box crashed today". If you do anyway, they will tell you that
you, the user, made an error (see the interview with Bill Gates in a
German magazine....) and that since it works now, you should shut up.
Those OSes are also somewhat more "predictable" than Linux. This means
that Excel might always be loaded in the exact same memory area.
Therefore when the bit-error occurs, it is always excel that gets it.
Excel will crash. Or excel will crash another application. Anyway, it
will seem to be a single application that fails, and not related to
memory.
What I am sure of is that a cleanly installed 1.2.13 Linux system
should be able to compile the kernel without any errors. Certainly no
sig-11 ones.
Really Linux and gcc stress your hardware more than other OSes. If you
need a non-linux thingy that stresses your hardware to the point of
crashing, you can try winstone. -- Jonathan Bright
([email protected])
_________________________________________________________________

QUESTION

Is it always signal 11?

ANSWER

Nope. Other signals like six and four also occur occasionally. Signal
11 is most common though.

As long as memory is getting corrupted, anything can happen. I'd
expect bad binaries to occur much more often than they really do.
Anyway, it seems that the odds are heavily biased towards gcc getting
a signal 11. Also seen:
* free_one_pmd: bad directory entry 00000008
* EXT2-fs warning (device 08:14): ext_2_free_blocks bit already
cleared for block 127916
* Internal error: bad swap device
* Trying to free nonexistent swap-page
* kfree of non-kmalloced memory ...
* scsi0: REQ before WAIT DISCONNECT IID
* Unable to handle kernel NULL pointer dereference at virtual
address c0000004
* put_page: page already exists 00000046
invalid operand: 0000
* Whee.. inode changed from under us. Tell Linus
* crc error -- System halted (During the uncompress of the Linux
kernel)
* Segmentation fault
* "unable to resolve symbol"
* make [1]: *** [sub_dirs] Error 139
make: *** [linuxsubdirs] Error 1
* X Windows can terminate with a "caught signal xx"

The first few ones are cases where the kernel "suspects" a
kernel-programming-error that is actually caused by the bad memory.
The last few point to application programs that end up with the
trouble.

-- S.G.de Marinis ([email protected])
-- Dirk Nachtmann ([email protected])

_________________________________________________________________

QUESTION

What do I do?

ANSWER

Things to try when you want to find out what is wrong...
* Disable the cache (BIOS) (or pull it out if it's on a "stick").
* Jumper the motherboard for lower CPU and bus speed.
* boot kernel with "linux mem=4M" (disables memory above 4Mb).
* Fiddle with settings of the refresh (BIOS)
* Try taking out half the memory. Try both halves in turn.
* Try borrowing memory from someone else. Preferably this should be
memory that runs Linux flawlessly in the other machine...
(Sillicon graphics Indy machines are also nice targets to borrow
memory from)
* If you want to verify if a solution really works try the
following:

tcsh
cd /usr/src/linux
make zImage
foreach i (0 1 2 3 4 5 6 7 8 9)
foreach j (0 1 2 3 4 5 6 7 8 9)
make clean;make zImage > log."$i"$j
end
end
All the resulting logfiles should be the same. (The first "make
zImage" makes sure that the dependencies are already
generated.....) This takes around 24 hours on a 100MHz pentium
with 16Mb of memory. (and about 3 months on a 386 with 4Mb :-).

The hardest part is that most people will be able to do all of the
above except borrowing memory from someone else, and it doesn't make a
difference. This makes it likely that it really is the RAM. Currently
RAM is the most pricy part of a PC, so you rather not have this
conclusion, but I'm sorry, I get lots of reactions that in the end
turn out to be the RAM. However don't despair just yet: your RAM may
not be completely wasted: you can always try to trade it in for
different or more RAM.
_________________________________________________________________

QUESTION

I had my RAMs tested in a RAM-tester device, and they are OK. Can't be
the RAM right?

ANSWER

Wrong. It seems that the errors that are currently occuring in RAMS
are not detectable by RAM-testers. It might be that your motherboard
is accessing the RAMs in dubious ways or otherwise messing up the RAM
while it is in YOUR computer. The advantage is that you can sell your
RAM to someone who still has confidence in his RAM-tester......
_________________________________________________________________

QUESTION

What are other possibilities?

ANSWER
Others have noted the following possibilities:
* The current pentium-optimizing-gcc fails with the default options
only on certain source files (floppy.c comes to mind :-). The
"triggers" are in the kernel, libc and in gcc itself. This is
easily diagnosed as "not a hardware problem" because it always
happens in the same place. You can either disable some
optimizations (try -fno-unroll-loops first) or use another gcc. --
Evan Cheng ([email protected])
* A badly misconfigured gcc -- some parts from one version, some
from another. After a few weeks I ended up re-installing from
scratch to get everything right. -- Richard H. Derr III
([email protected]).
* Gcc or the resulting application may terminate with sig11 when a
program is linked against the SCO libraries (which come with
iBCS). This occurs on some applications that have -L/lib in their
LDFLAGS....
* When compiling a kernel with an ELF compiler, but configured for
a.out (or the other way around, I forgot) you will get a signal 11
on the first call to "ld". This is easily identified as a software
problem, as it always occurs on the FIRST call to "ld" during the
build. -- REW
* An Ethernet card together with a badly configured PCI BIOS. If
your (ISA) Ethernet card has an aperture on the ISA bus, you might
need to configure it somewhere in the BIOS setup screens.
Otherwise the hardware would look on the PCI bus for the shared
memory area. As the ISA card can't react to the requests on the
PCI bus, you are reading empty "air". This can result in
segmentation faults and kernel crashes. -- REW
* Corrupted swap partition. Tony Nugent ([email protected])
reports he used to have this problem and solved it by an mkswap on
his swap partition. (Don't forget to type "sync" before doing
anything else after an mkswap. -- Louis J. LaBash Jr.
([email protected]))
* NE2000 card. Some cheap Ne2000 cards might mess up the system. --
Danny ter Haar ([email protected]) I personally might have had
similar problems, as my mail server crashed hard every now and
then (once a day). It now seems that 1.2.13 and lots of the 1.3.x
kernels have this bug. I haven't seen it in 1.3.48. Probably got
fixed somewhere in the meantime.... -- REW
* Power supply? No I don't think so. A modern heavy system with two
or three harddisk, both SCSI and IDE will not exceed 120 Watts or
so. If you have loads of old harddisks and old expansion cards the
power requirements will be higher, but still it is very hard to
reach the limits of the power supply. Of course some people manage
to find loads of old full-size harddisks and install them into
their big-tower. You can indeed overload a powersupply that way.
-- Greg Nicholson ([email protected]) A faulty power supply CAN
of course deliver marginal power, which causes all of the
malfunctioning that you read about in this file.... -- Thorsten
Kuehnemann ([email protected])
* An inconsistent ext2fs. Some circumstances can cause the kernel
code of the ext2 file system to result in Signal 11 for Gcc. --
Morten Welinder ([email protected])
* No or too little swap space. Gcc doesn't gracefully handle the
"out of memory" condition. -- Paul Brannan ([email protected])

_________________________________________________________________

QUESTION

I don't believe this. To whom has this happened?

ANSWER

Well for one it happened to me personally. But you don't have to
believe me. It also happened to:
* Johnny Stephens ([email protected])
* Dejan Ilic ([email protected])
* Rick Tessner ([email protected])
* David Fox ([email protected])
* Darren White ([email protected]) (L2 cache)
* Patrick J. Volkerding ([email protected])
* Jeff Coy Jr. ([email protected]) (Temp problems)
* Michael Blandford ([email protected]) (Temp problems: CPU fan
failed)
* Alex Butcher ([email protected]) (Memory waitstates)
* Richard Postgate ([email protected]) (VLB loading)
* Bert Meijs ([email protected]) (bad SIMMs)
* J. Van Stonecypher ([email protected])
* Mark Kettner ([email protected]) (bad SIMMs)
* Naresh Sharma ([email protected]) (30->72 converter)
* Rick Lim ([email protected]) (Bad cache)
* Scott Brumbaugh ([email protected])
* Paul Gortmaker ([email protected])
* Mike Tayter ([email protected]) (Something with the
cache)
* Benni ??? ([email protected]) (VLB Overloading)
* Oliver Schoett ([email protected]) (Cache jumper)
* Morten Welinder ([email protected])
* Warwick Harvey ([email protected]) (bit error in cache)
* Hank Barta ([email protected])
* Jeffrey J. Radice ([email protected]) (Ram voltage)
* Samuel Ramac ([email protected]) (CPU tops out)
* Andrew Eskilsson ([email protected]) (DRAM speed)
* W. Paul Mills ([email protected]) (CPU fan disconnected from CPU)
* Joseph Barone ([email protected]) (Bad cache)
* Philippe Troin ([email protected]) (delayed RAM timing
trouble)
* Koen D'Hondt ([email protected]) (more kernel error
messages)
* Bill Faust ([email protected]) (cache problem)
* Tim Middlekoop ([email protected]) (CPU temp: fan
installed)
* Andrew R. Cook ([email protected]) (bad cache)
* Allan Wind ([email protected]) (P66 overheating)
* Michael Tuschik ([email protected]) (gcc2.7.2p victim)
* R.C.H. Li ([email protected]) (Overclocking: ok for months...)
* Florin ([email protected]) (Overclocked CPU by vendor)
* Dale J March ([email protected]) (CPU overheating on laptop)
* Markus Schulte ([email protected]) (Bad RAM)
* Mark Davis ([email protected]) (Bad P120?)
* Josep Lladonosa i Capell ([email protected]) (PCI options
overoptimization)
* Emilio Federici ([email protected]) (P120 overheating)
* Conor McCarthy ([email protected]) (Bad SIMM)
* Matthias Petofalvi ([email protected]) ("Simmverter" problem)
* Jonathan Christopher Mckinney ([email protected]) (gcc2.7.2p victim)
* Greg Nicholson ([email protected]) (many old disks)
* Ismo Peltonen ([email protected]) (irq_unmasking)
* Daniel Pancamo ([email protected]) (70ns instead of 60 ns RAM)
* David Halls ([email protected])
* Mark Zusman ([email protected]) (Bad motherboard)
* Elizabeth Ayer ([email protected]) (Power management features)
* Thorsten Kuehnemann ([email protected])
*
* (Email me with your story, you might get to be mentioned here...
:-) ---- Update: I like to hear what happened to you. This will
allow me to guess what happens most, and keep this file as
accurate as possible. However I now have around 100 different
Email addresses of people who've had sig-11 problems. I don't
think that it is useful to keep on adding "random" people's names
on this list. What do YOU think?

_________________________________________________________________

I'm interested in new stories. If you have a problem and are unsure
about what it is, it may help to Email me at [email protected] .
My curiosity will usually drive me to answering your questions until
you find what the problem is..... (on the other hand, I do get pissed
when your problem is clearly described above :-)
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