Lab7
Chapter 5 device interrupt
a top half process kernel stack, system call (模式切换，数据拷贝) a bottom half hander 如何接受数据
consoleinit configures two interrupt . One is receive interrupt, another is (receiving) complete interrupt.
How to Read (software)
read system call make their way through consoleread , consoleread waits for input to arrive, and store input in cons.buf.
How UART handle input (hardware)
user type -> hardware asks for a interrupt. -> trap handler( trap.c ) check if it is device interrupt -> devintr according to scause (and Plic), calls uartintr .
uartintr read any chars to consoleintr. if user have typed entire line.consoleintr wakeup consoleread.
once consoleread read a whole line from cons.buf, it copy contents to user space and give control back to user.
How to write
timerintrrupt
only in machine mode, in start.c
实验
为E1000网卡加一个驱动
- 框架代码解析。首先是
kernel/net.c存放是一些有关mbuf的 库函数，针对mbufq的一些操作。实验里用不到。 kernel/net.h存放的是mbuf结构体的定义和一些宏函数。kernel/def_net.h存放的是一些E1000寄存器的宏kernel/e1000.c存放是有关 e1000 网卡 初始化，存储，转发的函数。
实现 e1000_tranmit 函数
free the last mbuf that was transmitted from that descriptor
Q:不太清楚这个 last mbuf 到底存放在哪里
A:放在 tx_buf array
stash away a pointer to the mbuf for later freeing.
Q: 这个 stash away 是要把这个buf指针存放在哪里呢？
A: 存放在 tx_buf array