static int win_chr_read_poll(CharDriverState *chr)
{
    WinCharState *s = chr->opaque;

    s->max_size = qemu_chr_be_can_write(chr);
    return s->max_size;
}
static int win_chr_read_poll(CharDriverState *chr)
{
    WinCharState *s = chr->opaque;

    s->max_size = qemu_chr_be_can_write(chr);
    return s->max_size;
}