My english language is very bad, sorry.

Recompiled by configure whith --enable-debug quit the problem,
I have testesd the serial port with minicom, it works!!!, sorry

.- steps
    .- configure
    .- make
    .- make install
    .- ifup tap0
    .- ifconfig
    .- run script 1
    .- run script 2
    .- Inside the machines whith minicom works ok.

script 1
--------
#!/bin/bash

echo "Launch machine 1"

qemu-system-i386 -m 128 -display sdl -cpu pentium \
-k es \
-net nic,vlan=0,macaddr=52:54:00:12:02:04,model=pcnet \
-net vde,vlan=0,sock=/var/run/vde2/tap0.ctl \
-serial unix:/tmp/com1,server,nowait \
-vga cirrus \
-boot c -hda "/home/VirtualMachines/Discos/Hispa70_1.vmdk" \
-cdrom "/home/VirtualMachines/CDROM/hf-7.0a.iso"

script 2
--------
#!/bin/bash

echo "Launch machine 2"

qemu-system-i386 -display sdl -cpu pentium \
-net nic,vlan=0,macaddr=52:54:00:12:FF:04,model=pcnet \
-net vde,vlan=0,sock=/var/run/vde2/tap0.ctl \
-serial unix:/tmp/com1,nowait \
-vga cirrus \
-boot c -hda "/home/VirtualMachines/Discos/Hispa70_2.vmdk"

.- configure
./configure --enable-debug --target-list=i386-softmmu,x86_64-softmmu,\
i386-linux-user,x86_64-linux-user --enable-vde --disable-vnc --enable-sdl \
--audio-drv-list=oss,alsa,sdl,esd,pa \
--audio-card-list=ac97,es1370,sb16,cs4231a,adlib,gus,hda &>status

.- Result of configure

Install prefix    /usr/local
BIOS directory    /usr/local/share/qemu
binary directory  /usr/local/bin
library directory /usr/local/lib
include directory /usr/local/include
config directory  /usr/local/etc
Manual directory  /usr/local/share/man
ELF interp prefix /usr/gnemul/qemu-%M
Source path       /home/javier/COMPILACIONES/qemu-1.2.0
C compiler        gcc
Host C compiler   gcc
Objective-C compiler gcc
CFLAGS            -g 
QEMU_CFLAGS       -fPIE -DPIE -m64 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing  -fstack-protector-all -Wendif-labels -Wmissing-include-dirs -Wempty-body -Wnested-externs -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-declaration -Wold-style-definition -Wtype-limits
LDFLAGS           -Wl,--warn-common -Wl,-z,relro -Wl,-z,now -pie -m64 -g 
make              make
install           install
python            python
smbd              /usr/sbin/smbd
host CPU          x86_64
host big endian   no
target list       i386-softmmu x86_64-softmmu i386-linux-user x86_64-linux-user
tcg debug enabled yes
gprof enabled     no
sparse enabled    no
strip binaries    no
profiler          no
static build      no
-Werror enabled   no
SDL support       yes
curses support    yes
curl support      no
mingw32 support   no
Audio drivers     oss alsa sdl esd pa
Extra audio cards ac97 es1370 sb16 cs4231a adlib gus hda
Block whitelist   
Mixer emulation   no
VirtFS support    no
VNC support       no
xen support       no
brlapi support    no
bluez  support    no
Documentation     yes
NPTL support      yes
GUEST_BASE        yes
PIE               yes
vde support       yes
Linux AIO support no
ATTR/XATTR support yes
Install blobs     yes
KVM support       yes
TCG interpreter   no
fdt support       no
preadv support    yes
fdatasync         yes
madvise           yes
posix_madvise     yes
uuid support      no
libcap-ng support no
vhost-net support yes
Trace backend     nop
Trace output file trace-<pid>
spice support     no
rbd support       no
xfsctl support    no
nss used          no
usb net redir     no
OpenGL support    yes
libiscsi support  no
build guest agent yes
seccomp support   no
coroutine backend ucontext

.- ifconfig
tap0      Link encap:Ethernet  direcciónHW 1e:b9:3d:8d:cd:29  
          Direc. inet:10.0.2.1  Difus.:10.0.2.255  Másc:255.255.255.0
          Dirección inet6: fe80::1cb9:3dff:fe8d:cd29/64 Alcance:Enlace
          ACTIVO DIFUSIÓN FUNCIONANDO MULTICAST  MTU:1500  Métrica:1
          Paquetes RX:0 errores:0 perdidos:0 overruns:0 frame:0
          Paquetes TX:89 errores:0 perdidos:0 overruns:0 carrier:0
          colisiones:0 long.colaTX:500 
          Bytes RX:0 (0.0 B)  TX bytes:17478 (17.4 KB)