MIT JOS Lab1 实验报告.pdf

JOS Lab1 实验报告 Exercise 1. Familiarize yourself with the assembly languagematerials available on the 6.828 reference page. You dont have to read them now, but youll almost certainly want to refer to some of this material when readin and writin x86 assembly. We do recommend readin the section The Syntax inBrennans Guide to InlineAssembly. Itgivesagood (andquitebrief)descriptionoftheATT assembly syntax well be usin with the GNU assembler in JOS. Exercise2. Use GDBs si (StepInstruction)commandto trace intothe ROM BIOSforafewmore instructions,andtryto guesswhat itmight bedoing. You might want to lookat Phil Storrs I/OPorts Description, as well as other materials on the 6.828 referencematerials page. No need to figure outallthedetails- justthegeneral ideaofwhattheBIOS isdoin first. Exercise 3. Take a lookat the labtools guide, especially the section on GDB commands. Even if youre familiar with GDB, this includes some esoteric GDB commands that are useful for OS work. Set a breakpoint at address 0x7c00, which iswhere the boot sector will be loaded.Continue execution until that breakpoint. Trace through the code in boot/boot.S, usin the source code and the disassembly file obj/boot/boot.asmtokeeptrackofwhere youare.Also usethex/icommand inGDB to disassemble sequences of instructions inthe boot loader,and compare the original boot loadersource code with both the disassembly inobj/boot/boot.asm and GDB. Trace intobootmain() inboot/main.c, and then intoreadsect(). Identify theexactassembly instructionsthatcorrespondtoeachofthe statements in readsect(). Trace through the rest of readsect() and back out into bootmain(), and identifythe begin and end of the forloop that readsthe remainin sectors of the kernel from the disk. Find out what code will run when the loop isfinished, set a breakpoint there, and continue to that breakpoint. Then step through the remainder of the boot loader. Be able to answer the followin questions