Centos – How to run Xvfb without root

Your format is off. See section 4.3 in this old doc or the Rules section of this newer version. Doug Palmer's Unreliable Guide is slightly dated but also a good resource.

You attempted:

! model layout variant = keycodes types compat symbols geometry
  current current current = current current current current current

Specifically, the righthand side of the = takes a single argument. On the ! line, the righthand side is a single type of file -- only one of {keycodes, types, compat, symbols, geometry} is allowed. On the other lines, the righthand side is a single argument meaning:

• a single file found in the type subdirectory (test1)
• a stanza defined in such a file (test1(foo))
• an addition to an earlier match (+test2 or +test2(bar))
• several files/stanzas joined together (test1+test1(foo)+test2(bar)+test3(baz))

The lefthand side is a filter; you can include as many as you want of these.

Basically, the rules build separate filesets for each of those types.

// KEYCODES SECTION
// load keycodes based on model specified
! model = keycodes
  test1  = test1
// ^^^^^^^^^^^^^^ 
//        "if model=test1, 
//         load the default in the file keycodes/test1"

// load keycodes based on layout specified
! layout = keycodes
  test1  = +test1(us)
// ^^^^^^^^^^^^^^
//        "if layout=test1, 
//         also load stanza "us" in the file keycodes/test1"


// all at once
! model layout variant option = keycodes
  test2 test2  test2   test2  = test1+test1(de)+test1(var2)+test1(opt2)
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^
//        "if model=test2 and layout=test2 and... ,
//         load the default stanza in file keycodes/test1,
//         then load stanza "de" in file keycodes/test1, ...


////////////////
// GEOMETRY SECTION
// load geometry based on model specified
! model = geometry
  test1 = test1
  *     = test3  // any other model

With these rules defined, you can play with setxkbmap -print to see your rules in action:

$ setxkbmap -I/path/to/my/xkb -rules test1 -model test1 -print
xkb_keymap {
        xkb_keycodes  { include "test1" };
        xkb_geometry  { include "test1" };
};
// no xkb_symbols or other sections of the map with only the rules above

$ setxkbmap -I/path/to/my/xkb -rules test2 -model test1 -layout test1 -print
xkb_keymap {
        xkb_keycodes  { include "test1+test1(us)"       };
        xkb_geometry  { include "test1" };
};

$ setxkbmap -I/path/to/my/xkb -rules test2 -model test2 -layout test2 -variant test2 -option test2 -print
xkb_keymap {
        xkb_keycodes  { include "test1+test1(us)+test1(var1)+test1(opt2)" };
        xkb_geometry  { include "test3" };
};

That's the basics of how the rules work, but of course it can get much more complicated.

• %l and %v are variables with the layout and variant (%m can also be used for the model)
• %(v) wraps the expansion in parentheses, so %l%(v) yields layout(variant)
• if multiple layouts/variants are defined, they're accessible as an array, and you'll need to add an index: %l[1] (%l will not work )
• if multiple layouts/variants are defined, add :2 (or :3 or :4) to restrict the files loaded to the 2nd (or 3rd or 4th) layout

Here's a very basic rules section that will pull in multiple layouts properly:

// setxkbmap -layout foo -variant foo1
! model    layout      =   symbols                                                                                                                                         
   *       *           =   %l%(v)                                                                                                                                                   

// setxkbmap -layout foo,bar -variant foo1,bar1                                                                                                                                                                                     
! model   layout[1]    =   symbols                                                                                                                                         
   *       *           =   %l[1]%(v[1])                                                                                                                                             

// setxkbmap -layout foo,bar -variant foo1,bar1                                                                                                                                                                                     
! model   layout[2]    =   symbols                                                                                                                                                 
   *       *           =   +%l[2]%(v[2]):2                                                                                                                                             

// setxkbmap -layout foo,bar,baz -variant foo1,bar1,baz1                                                                                                                                                                                     
! model   layout[3]    =   symbols                                                                                                                                                 
   *       *           =   +%l[3]%(v[3]):3                                                                                                                                             

// setxkbmap -layout foo,bar,baz,bat -variant foo1,bar1,baz1,bat1                                                                                                                                                                                     
 ! model   layout[4]   =   symbols                                                                                                                                             
   *       *           =   +%l[4]%(v[4]):4

Now you can load testing layouts into setxkbmap and see that they're being added.

$ setxkbmap -I/path/to/my/xkb -rules test -model test1 \
            -layout test1,test2,test3                  \
            -variant test1,testA,testB -print
xkb_keymap {
        xkb_keycodes  { include "test1+test1(us)" };
        xkb_symbols   { include "test1(test1)+test2(testA):2+test3(testB):3" };
        xkb_geometry  { include "test1" };
};

For some reason it works if you -print and pipe the output to xkbcomp:

setxkbmap \
    -I ~/.config/xkb/ \
    -rules evdev-local \
    -layout "my-us(mdvp)" \
    -print |
    xkbcomp -I ~/.config/xkb/ - "$DISPLAY"

I don’t think there is anything wrong with your layout. I tried setting it up with setxkbmap directly, but even with the -verbose option the output is not helpful:

Warning! Multiple definitions of rules file
         Using command line, ignoring X server
Warning! Multiple definitions of keyboard layout
         Using command line, ignoring X server
Trying to build keymap using the following components:
keycodes:   evdev+aliases(qwerty)
types:      complete
compat:     complete
symbols:    pc+my-us(mdvp)+inet(evdev)+terminate(ctrl_alt_bksp)
geometry:   pc(pc104)
Error loading new keyboard description

This is with the default verbose level. But even if I set it to 10, which is apparently the max level, it just outputs “locale is C” as well as where it tries to look for the rules file, in addition to the above. It does not output anything more about why it fails to load the keyboard description.

One of the reasons why I prefer to pipe to xkbcomp instead of just using setxkbmap is because the former seems to give better error messages.