1、退出快捷键
大家在用Qemu时经常会遇到要退出的情况。一般做法是使用ps或者lsof等命令找出qemu的进程ID,使用KILL命令杀死,该做法相当繁琐。实质上,Qemu已经设计了退出的快捷键:按下ctrl+a,之后按大写X。
2、代码分析
Qemu的所有交互输入时通过字符设备来实现的。具体退出的检查在路径“chardev/char-mux.c”文件的函数mux_proc_byte中。
/* ctrl+a 按键的标志位 */
int term_escape_char = 0x01; /* ctrl-a is used for escape */static int mux_proc_byte(Chardev *chr, MuxChardev *d, int ch)
{if (d->term_got_escape) {d->term_got_escape = 0;if (ch == term_escape_char) {goto send_char;}switch (ch) {case '?':case 'h':mux_print_help(chr);break;/* 如果已经识别到输入了ctrl+a,检查是否输入了x字符。若是,则执行Qemu退出的流程 */case 'x':{const char *term = "QEMU: Terminated\n\r";qemu_chr_write_all(chr, (uint8_t *)term, strlen(term));qmp_quit(NULL);break;}case 's':blk_commit_all();break;case 'b':qemu_chr_be_event(chr, CHR_EVENT_BREAK);break;case 'c':assert(d->mux_cnt > 0); /* handler registered with first fe *//* Switch to the next registered device */mux_set_focus(chr, (d->focus + 1) % d->mux_cnt);break;case 't':d->timestamps = !d->timestamps;d->timestamps_start = -1;d->linestart = 0;break;}} else if (ch == term_escape_char) {d->term_got_escape = 1;} else {send_char:return 1;}return 0;
}