size= 1024/*缓冲区（缓冲队列的长度）与/include/linux/tty.h line 14 #define TTY_BUF_SIZE 1024 相同 must be a power of two !And MUST be the same /* must be power of two ! and must match the value in tty_io.*/
/* these are the offsets into the read/write buffer structures */ rs_addr = 0 #串行端口号字段偏移（端口号是0x3f8 或0x2f8）。 head = 4 #缓冲区中头指针字段偏移 tail = 8 #缓冲区中尾指针字段偏移 proc_list = 12 #等待该缓冲的进程字段偏移 buf = 16 #缓冲区字段偏移
startup = 256 #当写队列里还剩256 个字符空间(WAKEUP_CHARS)时，我们就可以写 /* chars left in write queue when we restart it */
/* * These are the actual interrupt routines. They look where * the interrupt is coming from,and take appropriate action. */ .align 2 _rs1_interrupt:#串行端口1 中断处理程序入口点。 pushl $_table_list+8 #tty 表中对应串口1 的读写缓冲指针的地址入栈,linux-0.11\kernel\chr_drv\tty_io.c line 99 jmp rs_int .align 2 _rs2_interrupt:#串行端口2 中断处理程序入口点 pushl $_table_list+16 #tty 表中对应串口2 的读写缓冲指针的地址入栈,linux-0.11\kernel\chr_drv\tty_io.c line 99 rs_int: pushl %edx pushl %ecx pushl %ebx pushl %eax push %es push %ds /* as this is an interrupt, we cannot */ pushl $0x10 /* know that bs is ok. Load it */ pop %ds pushl $0x10 pop %es movl 24(%esp),%edx movl (%edx),%edx movl rs_addr(%edx),%edx addl $2,%edx /* interrupt ident. reg */ rep_int: xorl %eax,%eax inb %dx,%al testb $1,%al jne end cmpb $6,%al /*this shouldn
