Hello

I'm working on COMPAT_LINUX/amd64 and I experience unexpected problems.

When launching a Linux binary, the program starts but hangs before doing
any system call. Running gdb shows it is stopped on a hlt instruction.
What is it? halt? halt until when?

Thanks to sysctl proc.$$.stopexec I can use gdb to attach the program
before it starts. Stack and registers are correctly set up.

In order to find out what goes wrong, I'd like to trace the Linux binary
running on NetBSD using gdb. But gdb seems unable to trace. Anyone see
any reason why it could not?=20

$ gdb /emul/linux/bin/hello =20
(gdb) attach 632
Attaching to program: /emul/linux/bin/hello, process 632
_start () at ../sysdeps/x86_64/elf/start.S:48
48      ../sysdeps/x86_64/elf/start.S: No such file or directory.
        in ../sysdeps/x86_64/elf/start.S
Current language:  auto; currently asm
(gdb) info reg
rax            0x0      0
rbx            0x0      0
rcx            0x4001c0 4194752
rdx            0x0      0
rsi            0x0      0
rdi            0x0      0
rbp            0x0      0
rsp            0x7f7fffffe518   0x7f7fffffe518
r8             0x0      0
r9             0x0      0
r10            0x0      0
r11            0x0      0
r12            0x0      0
r13            0x0      0
r14            0x0      0
r15            0x0      0
rip            0x4001c0 0x4001c0 <_start>
eflags         0x246    582
ds             0x1f     31
es             0x17     23
fs             0x0      0
gs             0x0      0
fctrl          0x0      0
fstat          0x0      0
ftag           0x0      0
fiseg          0x0      0
fioff          0x0      0
foseg          0x0      0
fooff          0x0      0
fop            0x0      0
xmm0           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm1           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm2           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm3           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm4           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm5           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm6           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm7           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm8           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm9           {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm10          {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm11          {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm12          {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm13          {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm14          {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
xmm15          {f =3D {0x0, 0x0, 0x0, 0x0}}       {f =3D {0, 0, 0, 0}}
mxcsr          0x1f80   8064
(gdb) x/10i $pc
0x4001c0 <_start>:      xor    %rbp,%rbp
0x4001c3 <_start+3>:    mov    %rdx,%r9
0x4001c6 <_start+6>:    pop    %rsi
0x4001c7 <_start+7>:    mov    %rsp,%rdx
0x4001ca <_start+10>:   and    $0xfffffffffffffff0,%rsp
0x4001ce <_start+14>:   push   %rax
0x4001cf <_start+15>:   push   %rsp
0x4001d0 <_start+16>:   mov    $0x400bb0,%r8
0x4001d7 <_start+23>:   mov    $0x400b40,%rcx
0x4001de <_start+30>:   mov    $0x4002e0,%rdi
(gdb) b *0x4001c6
Breakpoint 1 at 0x4001c6: file ../sysdeps/x86_64/elf/start.S, line 66.
(gdb) si=20

[hang. neither si nor the breakpoint gave me back the control. Hit ^C]

^C
Program received signal SIGINT, Interrupt.
0x0000000000406a7b in _exit ()
(gdb) x/3i $pc
0x406a7b <_exit+43>:    hlt   =20
0x406a7c <_exit+44>:    jmp    0x406a53 <_exit+3>
0x406a7e <_exit+46>:    mov    %fs:0x0,%r8
(gdb) bt
#0  0x0000000000406a7b in _exit ()
#1  0x00000000004017d0 in __libc_fatal ()
#2  0x000000000040063b in __libc_start_main ()

--=20
Emmanuel Dreyfus
Publicit=E9 subliminale: achetez ce livre!
http://www.eyrolles.com/Informatique/Livre/9782212114638/livre-bsd.php
manu@netbsd.org