@User: I want to have all of the run-time setup files for sky130 in a place that is not user-specific. The default location (which today I finally got around to defining as the default) is "/usr/share/pdk/sky130A/". According to the way open_pdks is structured, all of the xschem files are copied into "/usr/share/pdk/sky130A/libs.tech/xschem/". The only things I changed in the "xschemrc" file are:

append XSCHEM_LIBRARY_PATH /usr/share/pdk/sky130A/libs.tech/xschem

and

set XSCHEM_START_WINDOW {/usr/share/pdk/sky130A/libs.tech/xschem/sky130_tests/top.sch}

My problem with this is that when I run xschem, I am getting a bunch of error messages

l_s_d(): Symbol not found: /usr/share/pdk/sky130A/libs.tech/xschem/sky130_tests/sky130_tests/_<name_of_symbol>_

. I am not sure why it has

sky130_tests

repeated twice, but that is why it is not finding the files. I have only specified that directory under

XSCHEM_START_WINDOW

, so I am not sure where it is picking up the repeated directory name.

@Tim Edwards is this going to be user configurable too? e.g. I have a separate drive with everything on and an

envsetup.sh

script in the project folder which sets up the env. variables to point to the relevant folders

@Tim Edwards The xschem symbol lookup for sky130 uses

libname/symbol.sym

, so the XSCHEM_LIBRARY_PATH paths should stop one level above the final directory:

set XSCHEM_LIBRARY_PATH /some/path

the actual location where the symbol is looked for will then be:

/some/path/libname/symbol.sym

For VLSI projects i often have realized that using only a component name (like for example 'inv.sym' or 'opamp.sym') is too weak, as there could be multiple matching device names in different directories. So all the example schematics i have in xschem use libname/symname.sym for referencing components. So if you have a base dir

/usr/share/pdk/sky130A/libs.tech/xschem

that contains these directories:

sky130_stdcells/

sky130_tests/

sky130_fd_pr/

define XSCHEM_LIBRARY_PATH in the following way:

set XSCHEM_LIBRARY_PATH ${XSCHEM_SHAREDIR}/xschem_library:/usr/share/pdk/sky130A/libs.tech/xschem

The first path component is xschem own symbol library (containing base elements, pins, labels, ideal spice primitives etc). Then you can if you want define a schematic to load at startup:

set XSCHEM_START_WINDOW sky130_tests/top.sch

note that xschem searches the XSCHEM_LIBRARY_PATH path list to find the actual schematic:

/usr/share/pdk/sky130A/libs.tech/xschem/sky130_tests/top.sch