Hi, we are part of the Mu3e research based at University of Bristol. We have a 
remote 32 bit frontend (raspberry pi) connected to a 64 bit Data Acquisition 
system.we are following the instructions at installation/quickstart linux/Build 
32-bit MIDAS libraries. when we execute the commands: 
[mhostpc] cd /home/packages/midas
[mhostpc] make linux32             

we get an error:

make NO_ROOT=1 NO_MYSQL=1 NO_ODBC=1 NO_SQLITE=1 OS_DIR=linux-m32 USERFLAGS=-m32
make[1]: Entering directory `/home/hh19285/packages/midas'
g++ -m32 -c -g -O2 -Wall -Wno-strict-aliasing -Wuninitialized -Iinclude -
Idrivers -Imxml -Imscb/include -DHAVE_FTPLIB -D_LARGEFILE64_SOURCE -DHAVE_ZLIB -
DHAVE_MSCB -DHAVE_MONGOOSE6 -DMG_ENABLE_THREADS -DMG_DISABLE_CGI -DMG_ENABLE_SSL 
-DOS_LINUX -fPIC -Wno-unused-function -o lib/crc32c.o src/crc32c.cxx
src/crc32c.cxx: In function ‘uint32_t crc32c_hw(uint32_t, const void*, size_t)’:
src/crc32c.cxx:283:66: error: ‘asm’ operand has impossible constraints
                     : "r"(next), "0"(crc0), "1"(crc1), "2"(crc2));
                                                                  ^
src/crc32c.cxx:303:66: error: ‘asm’ operand has impossible constraints
                     : "r"(next), "0"(crc0), "1"(crc1), "2"(crc2));
                                                                  ^
src/crc32c.cxx: In function ‘uint32_t crc32c(uint32_t, const void*, size_t)’:
src/crc32c.cxx:348:34: error: PIC register clobbered by ‘%ebx’ in ‘asm’
                 : "%ebx", "%edx"); \
                                  ^
src/crc32c.cxx:362:5: note: in expansion of macro ‘SSE42’
     SSE42(sse42);
     ^
make[1]: *** [lib/crc32c.o] Error 1
make[1]: Leaving directory `/home/hh19285/packages/midas'
make: *** [linux32] Error 2

Could you please help with getting past this? otherwise we may need to change 
our whole experimental setup.

Thank you in advance

Why don't your try the (yet undocumented) new installation procedure:

$ git clone https://bitbucket.com/tmidas/midas --recursive
$ cd midas
$ mkdir build
$ cd build
$ cmake ..
$ make
$ make install

In case your RPi does not have cmake pre-installed, you need

$ sudo apt-get install cmake.

Works for my RPi.

Best,
Stefan

Update: "make" instead of "make linux32" should also work. I believe the "linux32" target came 
from some special case at TRIUMF for some FPGA embedded linux, which is not applicable for 
the Raspberry Pi.

Note that the build process has to be initiated on the Raspberry Pi, NOT a host PC.

Stefan

Yikes, the error is in the CRC library. The assembly-optimized crc32c function fails to build, and the 
error does not look familiar to me. I do not see this error here. What is your host system ("uname -
a") and what is your gcc ("gcc -v")?

BTW, "make linux32" will build an Intel 32-bit version (see "-m32" in "man gcc"). For ARM 32-bit 
you need a different switch, I think, also depending how you are cross-compiling it.

For straight cross-compilation, look at the Makefile target "make linuxarm" (you will need to change 
the location of your ARM gcc cross-compiler).

For running MIDAS frontend on the Raspberry Pi 3, I build MIDAS on the Pi3 itself, the machine is big 
enough to run CentOS7 linux and gcc to build the full MIDAS.

But if you have a different cross-compilation scheme, I am happy to help you and to add your 
scheme to the MIDAS Makefile. We can start by looking at "uname -a" and "gcc -v" and "lsb_release 
-a" (if you have it).

K.O.


> Hi, we are part of the Mu3e research based at University of Bristol. We have a 
> remote 32 bit frontend (raspberry pi) connected to a 64 bit Data Acquisition 
> system.we are following the instructions at installation/quickstart linux/Build 
> 32-bit MIDAS libraries. when we execute the commands: 
> [mhostpc] cd /home/packages/midas
> [mhostpc] make linux32             
> 
> we get an error:
> 
> make NO_ROOT=1 NO_MYSQL=1 NO_ODBC=1 NO_SQLITE=1 OS_DIR=linux-m32 USERFLAGS=-
m32
> make[1]: Entering directory `/home/hh19285/packages/midas'
> g++ -m32 -c -g -O2 -Wall -Wno-strict-aliasing -Wuninitialized -Iinclude -
> Idrivers -Imxml -Imscb/include -DHAVE_FTPLIB -D_LARGEFILE64_SOURCE -DHAVE_ZLIB -
> DHAVE_MSCB -DHAVE_MONGOOSE6 -DMG_ENABLE_THREADS -DMG_DISABLE_CGI -
DMG_ENABLE_SSL 
> -DOS_LINUX -fPIC -Wno-unused-function -o lib/crc32c.o src/crc32c.cxx
> src/crc32c.cxx: In function ‘uint32_t crc32c_hw(uint32_t, const void*, size_t)’:
> src/crc32c.cxx:283:66: error: ‘asm’ operand has impossible constraints
>                      : "r"(next), "0"(crc0), "1"(crc1), "2"(crc2));
>                                                                   ^
> src/crc32c.cxx:303:66: error: ‘asm’ operand has impossible constraints
>                      : "r"(next), "0"(crc0), "1"(crc1), "2"(crc2));
>                                                                   ^
> src/crc32c.cxx: In function ‘uint32_t crc32c(uint32_t, const void*, size_t)’:
> src/crc32c.cxx:348:34: error: PIC register clobbered by ‘%ebx’ in ‘asm’
>                  : "%ebx", "%edx"); \
>                                   ^
> src/crc32c.cxx:362:5: note: in expansion of macro ‘SSE42’
>      SSE42(sse42);
>      ^
> make[1]: *** [lib/crc32c.o] Error 1
> make[1]: Leaving directory `/home/hh19285/packages/midas'
> make: *** [linux32] Error 2
> 
> Could you please help with getting past this? otherwise we may need to change 
> our whole experimental setup.
> 
> Thank you in advance

Thanks for your advice. We now have Midas installed on both our machines (remote machine-Rpi &
hostmachine-Centos). 

=========================================================================================================
One the host machine:
[hh19285@it038146 bin]$ uname -a
Linux it038146.users.bris.ac.uk 3.10.0-957.21.2.el7.x86_64 #1 SMP Wed Jun 5 14:26:44 UTC 2019 x86_64 x86_64
x86_64 GNU/Linux
[hh19285@it038146 bin]$ uname -a
Linux it038146.users.bris.ac.uk 3.10.0-957.21.2.el7.x86_64 #1 SMP Wed Jun 5 14:26:44 UTC 2019 x86_64 x86_64
x86_64 GNU/Linux
[hh19285@it038146 bin]$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id --with-linker-hash-style=gnu
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto --enable-plugin --enable-initfini-array
--disable-libgcj --with-isl=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/isl-install
--with-cloog=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/cloog-install
--enable-gnu-indirect-function --with-tune=generic --with-arch_32=x86-64 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.8.5 20150623 (Red Hat 4.8.5-36) (GCC) 
[hh19285@it038146 bin]$ lsb_release -a
LSB Version:	:core-4.1-amd64:core-4.1-noarch
Distributor ID:	CentOS
Description:	CentOS Linux release 7.6.1810 (Core) 
Release:	7.6.1810
Codename:	Core

===========================================================================================================
On remote machine:
pi@raspberrypi:~/packages/midas/bin $ uname -a
Linux raspberrypi 4.19.42-v7+ #1219 SMP Tue May 14 21:20:58 BST 2019 armv7l GNU/Linux
pi@raspberrypi:~/packages/midas/bin $ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabihf/6/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../src/configure -v --with-pkgversion='Raspbian 6.3.0-18+rpi1+deb9u1'
--with-bugurl=file:///usr/share/doc/gcc-6/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-6
--program-prefix=arm-linux-gnueabihf- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/
--enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new
--enable-gnu-unique-object --disable-libitm --disable-libquadmath --enable-plugin --with-system-zlib
--disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-6-armhf/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-6-armhf
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-6-armhf --with-arch-directory=arm
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar --with-target-system-zlib --enable-objc-gc=auto
--enable-multiarch --disable-sjlj-exceptions --with-arch=armv6 --with-fpu=vfp --with-float=hard
--enable-checking=release --build=arm-linux-gnueabihf --host=arm-linux-gnueabihf --target=arm-linux-gnueabihf
Thread model: posix
gcc version 6.3.0 20170516 (Raspbian 6.3.0-18+rpi1+deb9u1) 
pi@raspberrypi:~/packages/midas/bin $ lsb_release -a
No LSB modules are available.
Distributor ID:	Raspbian
Description:	Raspbian GNU/Linux 9.9 (stretch)
Release:	9.9
Codename:	stretch







> Yikes, the error is in the CRC library. The assembly-optimized crc32c function fails to build, and the 
> error does not look familiar to me. I do not see this error here. What is your host system ("uname -
> a") and what is your gcc ("gcc -v")?
> 
> BTW, "make linux32" will build an Intel 32-bit version (see "-m32" in "man gcc"). For ARM 32-bit 
> you need a different switch, I think, also depending how you are cross-compiling it.
> 
> For straight cross-compilation, look at the Makefile target "make linuxarm" (you will need to change 
> the location of your ARM gcc cross-compiler).
> 
> For running MIDAS frontend on the Raspberry Pi 3, I build MIDAS on the Pi3 itself, the machine is big 
> enough to run CentOS7 linux and gcc to build the full MIDAS.
> 
> But if you have a different cross-compilation scheme, I am happy to help you and to add your 
> scheme to the MIDAS Makefile. We can start by looking at "uname -a" and "gcc -v" and "lsb_release 
> -a" (if you have it).
> 
> K.O.
> 
> 
> > Hi, we are part of the Mu3e research based at University of Bristol. We have a 
> > remote 32 bit frontend (raspberry pi) connected to a 64 bit Data Acquisition 
> > system.we are following the instructions at installation/quickstart linux/Build 
> > 32-bit MIDAS libraries. when we execute the commands: 
> > [mhostpc] cd /home/packages/midas
> > [mhostpc] make linux32             
> > 
> > we get an error:
> > 
> > make NO_ROOT=1 NO_MYSQL=1 NO_ODBC=1 NO_SQLITE=1 OS_DIR=linux-m32 USERFLAGS=-
> m32
> > make[1]: Entering directory `/home/hh19285/packages/midas'
> > g++ -m32 -c -g -O2 -Wall -Wno-strict-aliasing -Wuninitialized -Iinclude -
> > Idrivers -Imxml -Imscb/include -DHAVE_FTPLIB -D_LARGEFILE64_SOURCE -DHAVE_ZLIB -
> > DHAVE_MSCB -DHAVE_MONGOOSE6 -DMG_ENABLE_THREADS -DMG_DISABLE_CGI -
> DMG_ENABLE_SSL 
> > -DOS_LINUX -fPIC -Wno-unused-function -o lib/crc32c.o src/crc32c.cxx
> > src/crc32c.cxx: In function ‘uint32_t crc32c_hw(uint32_t, const void*, size_t)’:
> > src/crc32c.cxx:283:66: error: ‘asm’ operand has impossible constraints
> >                      : "r"(next), "0"(crc0), "1"(crc1), "2"(crc2));
> >                                                                   ^
> > src/crc32c.cxx:303:66: error: ‘asm’ operand has impossible constraints
> >                      : "r"(next), "0"(crc0), "1"(crc1), "2"(crc2));
> >                                                                   ^
> > src/crc32c.cxx: In function ‘uint32_t crc32c(uint32_t, const void*, size_t)’:
> > src/crc32c.cxx:348:34: error: PIC register clobbered by ‘%ebx’ in ‘asm’
> >                  : "%ebx", "%edx"); \
> >                                   ^
> > src/crc32c.cxx:362:5: note: in expansion of macro ‘SSE42’
> >      SSE42(sse42);
> >      ^
> > make[1]: *** [lib/crc32c.o] Error 1
> > make[1]: Leaving directory `/home/hh19285/packages/midas'
> > make: *** [linux32] Error 2
> > 
> > Could you please help with getting past this? otherwise we may need to change 
> > our whole experimental setup.
> > 
> > Thank you in advance

Dear Midas experts, 

I'm running into something which looks like an initialization problem. 
I have a mfe.cxx-style frontend which introduces an equipment of the EQ_PERIODIC type (EQ_PERIODIC-only!). 
When Midas enters the running state, I see the frontend crashing. 
Stepping through the code shows that the frontend is crashing because its equipment has been ignored 
by the initialize_equipment@mfe.cxx - see
 
https://bitbucket.org/tmidas/midas/src/5d0dae001712164ae43137dced2fbbb594f0201e/src/mfe.cxx#lines-630

Is there an assumption that the initialization of the EQ_PERIODIC-only equipment is the user responsibility? 
Or EQ_PERIODIC should always come paired with some other type?

-- many thanks, regards, Pasha

There is no requirement that you pair an EQ_PERIODIC with an EQ_TRIGGER. Take for exmaple

  midas/examples/experiment/frontend.cxx

and remove there the triggered event. The frontend runs happily with the periodic event only (I just tried that myself). You have probably some problem in 
your event definition. Start with the running example frontend, and add your code line by line until you see the problem.

Stefan

> There is no requirement that you pair an EQ_PERIODIC with an EQ_TRIGGER. Take for exmaple
> 
>   midas/examples/experiment/frontend.cxx
> 
> and remove there the triggered event. The frontend runs happily with the periodic event only (I just tried that myself). You have probably some problem in 
> your event definition. Start with the running example frontend, and add your code line by line until you see the problem.

Hi Stefan, thank you very much! 

As the pointer to the readout function and pointers to device drivers are all defined in the same structure (EQUIPMENT), 
I was naively assuming that the readout function should be set during the class driver initialization.
Now it is clear that the equipment responding to EQ_PERIODIC events doesn't have to have drivers, 
and specifying the readout function is the responsibility of the user.

I got around exactly this way yesterday, but was thinking that I was hacking the system :)
 
-- regards, Pasha

I'm still trying to upgrade my MIDAS system to midas-2019-09-i. Most frontends work fine with the modifications already discussed.
However, I ran into some trouble with the epics frontend. Even with the modifications it throws a lot of warnings and errors (see attached log file). I can reduce the errors with -fpermissive, but the following two errors are persistent:

/home/ays/packages/midas/drivers/device/epics_ca.cxx:167:38: error: ‘ca_create_channel’ was not declared in this scope
            , &(info->caid[i].chan_id))

/home/ays/packages/midas/drivers/device/epics_ca.cxx:178:37: error: ‘ca_create_subscription’ was not declared in this scope
            , &(info->caid[i].evt_id))

This is strange because the functions seem to be declared in base/include/cadef.h along with similar functions that don't throw an error.
I don't know what's going on. The frontend which is almost identical to the example in the midas distribution compiles without warnings or errors under the Midas2017 version. 

> I'm still trying to upgrade my MIDAS system to midas-2019-09-i. Most frontends work fine with the modifications already discussed.
> However, I ran into some trouble with the epics frontend. Even with the modifications it throws a lot of warnings and errors (see attached log file). I can reduce the errors with -fpermissive, but the following two errors are persistent:
> 
> /home/ays/packages/midas/drivers/device/epics_ca.cxx:167:38: error: ‘ca_create_channel’ was not declared in this scope
>             , &(info->caid[i].chan_id))
> 
> /home/ays/packages/midas/drivers/device/epics_ca.cxx:178:37: error: ‘ca_create_subscription’ was not declared in this scope
>             , &(info->caid[i].evt_id))
> 
> This is strange because the functions seem to be declared in base/include/cadef.h along with similar functions that don't throw an error.
> I don't know what's going on. The frontend which is almost identical to the example in the midas distribution compiles without warnings or errors under the Midas2017 version. 

Hi, Peter - it looks like epics_ca.cxx needs to be updated to proper C++ (char* warnings, etc).

As for the "function not declared" errors, it's the C++ way to say "you are calling a function with wrong arguments",
again, something I should be able to fix without too much trouble.

Thank you for reporting this, the midas version of epics_ca.cxx definitely needs fixing.

K.O.

I fixed the compiler errors in epics_ca.cxx, can you try again? (see https://bitbucket.org/tmidas/midas/commits/)

But, I do not see errors with ca_create_channel() and ca_create_subscription().

Maybe I am using the wrong epics. If you still see these errors, let me know what epics you have, I will try the same one.

This is what I do (and I get epics 7.0).

mkdir -p $HOME/git
cd $HOME/git
git clone https://git.launchpad.net/epics-base
cd epics-base
make
ls -l include/cadef.h
ls -l lib/darwin-x86/libca.a # also linux-x86/libca.a

K.O.

> > I'm still trying to upgrade my MIDAS system to midas-2019-09-i. Most frontends work fine with the modifications already discussed.
> > However, I ran into some trouble with the epics frontend. Even with the modifications it throws a lot of warnings and errors (see attached log file). I can reduce the errors with -fpermissive, but the following two errors are persistent:
> > 
> > /home/ays/packages/midas/drivers/device/epics_ca.cxx:167:38: error: ‘ca_create_channel’ was not declared in this scope
> >             , &(info->caid[i].chan_id))
> > 
> > /home/ays/packages/midas/drivers/device/epics_ca.cxx:178:37: error: ‘ca_create_subscription’ was not declared in this scope
> >             , &(info->caid[i].evt_id))
> > 
> > This is strange because the functions seem to be declared in base/include/cadef.h along with similar functions that don't throw an error.
> > I don't know what's going on. The frontend which is almost identical to the example in the midas distribution compiles without warnings or errors under the Midas2017 version. 
> 
> Hi, Peter - it looks like epics_ca.cxx needs to be updated to proper C++ (char* warnings, etc).
> 
> As for the "function not declared" errors, it's the C++ way to say "you are calling a function with wrong arguments",
> again, something I should be able to fix without too much trouble.
> 
> Thank you for reporting this, the midas version of epics_ca.cxx definitely needs fixing.
> 
> K.O.

Hi Konstantin,
I have EPICS Base Release 3.14.8.2 and got your example running with it, though I had to make one change.
For some reason it wouldn't find libca.so, but when I linked the static library libca.a instead, it worked.
Also my midas frontend works now with the updated epics_ca.xx. There was a problem with an old local version of cadef.h
(probably a leftover from some previous testing). After removing it everything compiled well.

Thanks,
Peter


> I fixed the compiler errors in epics_ca.cxx, can you try again? (see https://bitbucket.org/tmidas/midas/commits/)
> 
> But, I do not see errors with ca_create_channel() and ca_create_subscription().
> 
> Maybe I am using the wrong epics. If you still see these errors, let me know what epics you have, I will try the same one.
> 
> This is what I do (and I get epics 7.0).
> 
> mkdir -p $HOME/git
> cd $HOME/git
> git clone https://git.launchpad.net/epics-base
> cd epics-base
> make
> ls -l include/cadef.h
> ls -l lib/darwin-x86/libca.a # also linux-x86/libca.a
> 
> K.O.
> 
> > > I'm still trying to upgrade my MIDAS system to midas-2019-09-i. Most frontends work fine with the modifications already discussed.
> > > However, I ran into some trouble with the epics frontend. Even with the modifications it throws a lot of warnings and errors (see attached log file). I can reduce the errors with -fpermissive, but the following two errors are persistent:
> > > 
> > > /home/ays/packages/midas/drivers/device/epics_ca.cxx:167:38: error: ‘ca_create_channel’ was not declared in this scope
> > >             , &(info->caid[i].chan_id))
> > > 
> > > /home/ays/packages/midas/drivers/device/epics_ca.cxx:178:37: error: ‘ca_create_subscription’ was not declared in this scope
> > >             , &(info->caid[i].evt_id))
> > > 
> > > This is strange because the functions seem to be declared in base/include/cadef.h along with similar functions that don't throw an error.
> > > I don't know what's going on. The frontend which is almost identical to the example in the midas distribution compiles without warnings or errors under the Midas2017 version. 
> > 
> > Hi, Peter - it looks like epics_ca.cxx needs to be updated to proper C++ (char* warnings, etc).
> > 
> > As for the "function not declared" errors, it's the C++ way to say "you are calling a function with wrong arguments",
> > again, something I should be able to fix without too much trouble.
> > 
> > Thank you for reporting this, the midas version of epics_ca.cxx definitely needs fixing.
> > 
> > K.O.

> I have EPICS Base Release 3.14.8.2 and got your example running with it...

Ok, good.

> I had to make one change.
> For some reason it wouldn't find libca.so, but when I linked the static library libca.a instead, it worked.

Yes, libca.a is what I see in my epics, too. I recommend static linking (libxxx.a instead of libxxx.so) as it eliminates
all possible problems with "cannot find the shared library" and "found the wrong shared library" and "found
a shared library from a different version of epics".

> Also my midas frontend works now with the updated epics_ca.xx. There was a problem with an old local version of cadef.h
> (probably a leftover from some previous testing). After removing it everything compiled well.

Ok. good. I also see some old epics header files in the midas repository. I guess I should remove them.

K.O.


> 
> Thanks,
> Peter
> 
> 
> > I fixed the compiler errors in epics_ca.cxx, can you try again? (see https://bitbucket.org/tmidas/midas/commits/)
> > 
> > But, I do not see errors with ca_create_channel() and ca_create_subscription().
> > 
> > Maybe I am using the wrong epics. If you still see these errors, let me know what epics you have, I will try the same one.
> > 
> > This is what I do (and I get epics 7.0).
> > 
> > mkdir -p $HOME/git
> > cd $HOME/git
> > git clone https://git.launchpad.net/epics-base
> > cd epics-base
> > make
> > ls -l include/cadef.h
> > ls -l lib/darwin-x86/libca.a # also linux-x86/libca.a
> > 
> > K.O.
> > 
> > > > I'm still trying to upgrade my MIDAS system to midas-2019-09-i. Most frontends work fine with the modifications already discussed.
> > > > However, I ran into some trouble with the epics frontend. Even with the modifications it throws a lot of warnings and errors (see attached log file). I can reduce the errors with -fpermissive, but the following two errors are persistent:
> > > > 
> > > > /home/ays/packages/midas/drivers/device/epics_ca.cxx:167:38: error: ‘ca_create_channel’ was not declared in this scope
> > > >             , &(info->caid[i].chan_id))
> > > > 
> > > > /home/ays/packages/midas/drivers/device/epics_ca.cxx:178:37: error: ‘ca_create_subscription’ was not declared in this scope
> > > >             , &(info->caid[i].evt_id))
> > > > 
> > > > This is strange because the functions seem to be declared in base/include/cadef.h along with similar functions that don't throw an error.
> > > > I don't know what's going on. The frontend which is almost identical to the example in the midas distribution compiles without warnings or errors under the Midas2017 version. 
> > > 
> > > Hi, Peter - it looks like epics_ca.cxx needs to be updated to proper C++ (char* warnings, etc).
> > > 
> > > As for the "function not declared" errors, it's the C++ way to say "you are calling a function with wrong arguments",
> > > again, something I should be able to fix without too much trouble.
> > > 
> > > Thank you for reporting this, the midas version of epics_ca.cxx definitely needs fixing.
> > > 
> > > K.O.

>
> > I have EPICS Base Release 3.14.8.2 ...
>

For the record, according to https://epics.anl.gov/

the 3.14 branch is "Closed, please upgrade!"
the 3.15 branch seems to be the current "stable" branch, and
the 7.0 branch is the "current release"

I forget which version of EPICS is currently recommended by the TRIUMF controls group. I will have to go and ask them.

K.O.

The documentation fro the Elog ODB tree here:
https://midas.triumf.ca/MidasWiki/index.php//Elog_ODB_tree#Url

says:

The Built-in elog will ignore this key.

If using an Built-in Elog, this key must NOT be present.

I assume this is an artifact from amending the documentation, but it's unclear if 
the key has to be removed or not. I.e. if the key exists and is empty, will the 
built-in elog work? In what way will it break?

Hi,

We have recently been changing the code in mhttpd that maps custom web pages and resources to 
particular files on the server file system.  Ie, changing the code that uses the ODB keys in /Custom to 
map a web address like 

http://myhost:8081/CS/MyCustomPage 

to some file like

/home/user/resource/mypage.html

This mapping gets complicated when you use the /Custom/Path key to specify a location for web 
resources like images.  We have tried to summarize how the current system works on the wiki

https://midas.triumf.ca/MidasWiki/index.php//Custom_ODB_tree

Please provide any suggestions on how either the documentation or the actual algorithm can be 
improved.