Linux with MMU on NEEK

Hi.

About 'fltk' demo programs, the 'Segmentation fault' is caused by a wrong linking process. All 'fltk' demo programs use the library 'libX11.so.6' and this library uses the nano-X library. But the nano-X library is generated as a static library i.e. 'libnano-X.a' in default configrations. This 'libnano-X.a' uses 'libc' and 'libc' is a shared library. So the generated code for the function 'GrSetErrorHandler' in libX11.so.6 is as follows.

00017328 <GrSetErrorHandler>:
   17328:    defffc04     addi    sp,sp,-16
   1732c:    dc400015     stw    r17,0(sp)
   17330:    044000f4     movhi    r17,3
   17334:    8c63be04     addi    r17,r17,-28936
   17338:    dd400215     stw    r21,8(sp)
   1733c:    202b883a     mov    r21,r4
   17340:    8809883a     mov    r4,r17
   17344:    dfc00315     stw    ra,12(sp)
   17348:    dcc00115     stw    r19,4(sp)
   1734c:    0008ac40     call    8ac4 <_init+0x408>     <-----
   17350:    d4e29517     ldw    r19,-30124(gp)
   17354:    8809883a     mov    r4,r17
   17358:    d5629515     stw    r21,-30124(gp)
   1735c:    00087a00     call    87a0 <_init+0xe4>       <-----
   17360:    9805883a     mov    r2,r19
   17364:    dfc00317     ldw    ra,12(sp)
   17368:    dd400217     ldw    r21,8(sp)
   1736c:    dcc00117     ldw    r19,4(sp)
   17370:    dc400017     ldw    r17,0(sp)
   17374:    dec00404     addi    sp,sp,16
   17378:    f800283a     ret

When we execute this, the real code is as follows.

0x2aae3328:    addi    sp,sp,-16 
0x2aae332c:    stw    r17,0(sp) 
0x2aae3330:    movhi    r17,3 
0x2aae3334:    addi    r17,r17,-28936 
0x2aae3338:    stw    r21,8(sp) 
0x2aae333c:    mov    r21,r4 
0x2aae3340:    mov    r4,r17 
0x2aae3344:    stw    ra,12(sp) 
0x2aae3348:    stw    r19,4(sp) 
0x2aae334c:    call    0x20008ac4          <-----
0x2aae3350:    ldw    r19,-30124(gp) 
0x2aae3354:    mov    r4,r17 
0x2aae3358:    stw    r21,-30124(gp) 
0x2aae335c:    call    0x200087a0         <-----
0x2aae3360:    mov    r2,r19 
0x2aae3364:    ldw    ra,12(sp) 
0x2aae3368:    ldw    r21,8(sp) 
0x2aae336c:    ldw    r19,4(sp) 
0x2aae3370:    ldw    r17,0(sp) 
0x2aae3374:    addi    sp,sp,16 
0x2aae3378:    ret 

Of cource these relocations are wrong and the calling address '0x20008ac4' etc. will make 'Segmentation faults' .

The easy way to avoid this failure is to make the nano-X library as a shared library. Inside the config file '/home/**/nios2-linux/uClinux-dist/user/microwin/src/config', change

# #################################################################### #  Libraries to build: microwin, nano-X, nanowidget, object frameworks# # ###################################################################
MICROWIN               = Y
NANOX                = Y
SHAREDLIBS                 = Y        <---- Change this from N to Y
OBJFRAMEWORK       = N

flush the contents of the directory ' /home/**/nios2-linux/uClinux-dist/user/microwin/src/lib' and libX11.so.6.2 in '/home/**/nios2-linux/uClinux-dist/user/microwin/nxlib/nxlib-0.45', we can get new 'libX11.so.6.2' by 'make'. After copying the new library with 'libnano-X.so' and 'libstdc++.so.6', we can evoke 'hello', 'clock' and 'editor' successfully. But 'valuator' will generate SEGV, when I touch its dials. Why?

Kazu