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Questions tagged [xv6]

xv6 is a small Unix-like teaching operating system made by MIT for its 6.828 OS course. It is inspired by Unix Version 6.

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Register pointer in creating threads in xv6

I want to create a thread in xv6 by using a system call "clone()", but I am confused about the stack creation, since if I want to create a thread, I need to create the corresponding register pointer such like ebp, esp, eip. But I don't know how to…
zyz
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How to get the page directory of a pointer in xv6

Here is my 'translate()' in proc.c I want to get the physical address given the virtual address of a pointer, but I don't know how to get the pointers pgdir(page directory)... int translate(void* vaddr) { cprintf("vaddr = %p\n",vaddr); int…
zyz
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Compile XV6 on MAC

Before compile XV6, I have read this page to build my own compiler toolchain. And the result is similar. ➜ xv6-public git:(master) ✗ i386-jos-elf-objdump -i BFD header file version (GNU Binutils) 2.27 elf32-i386 (header little endian, data little…
icecity96
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Program statically linked to newlib failed to run in xv6

I encountered some problems when running newlib-linked programs in xv6. (This is the newlib port I have used) I used this toolchain to compile the newlib. There aren't any problems in compiling and I do get libc.a, libm.a and other library…
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Xv6 stack frame - return value of eip getting mangled?

I have the following code attempting to run in xv6: void handle_signal(siginfo_t info) { printf(1, "Caught signal %d...\n", info.signum); if (info.signum == SIGFPE) printf(1, "TEST PASSED\n"); else printf(1, "TEST FAILED:…
Mikey Chen
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Race Condition in xv6

I am a newbie in the field of OS and trying to learn it by hacking into xv6.My doubt is can we decide before making a call to fork whether to run parent or child using system calls.i,e i can have a function pass an argument to kernel space and…
user3274335
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Executing a Stopped Process in XV6

I wrote two new system calls and add them to the xv6 OS kernel. So using one system call I can save process state and using the other one I can reload the previous state and continue. the problem is in the reloading section. is it enough to reload…
Mohammad Mahdi KouchakYazdi
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Process Migration in xv6 OS

I want to write a program that can save a process's state when it exits in a file and another program to reload this process's state and run it from were it left in xv6 OS. Something like keeping processes' state when you are changing among…
Sparrow7000
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xv6 operating system - Implementation of triple indirection

The xv6 mkfs.c file declare the variables: int nblocks = 985; int nlog = LOGSIZE; int ninodes = 200; int size = 1024; That declaration should work properly with inode that have 12 direct blocks and 1 indirect block, what i don't understand is why…
avivar
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XV6 crashes when trying to implement triple indirection in xv6 operating system

The original xv6-rev7 operating system contains: 12 directed blocks 1 indirect blcok(points to 128 blocks) This means we have 140 blocks. Each block's size is 512KB ==> 512 * 140 = 71,680 ~= 70KB is the limit of file's size in xv6. I want to…
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qemu request for a disc image

I am trying to get qemu up and running with xv6 but I am having some trouble with compiling xv6. what are the types of disc images that qemu accepts. for instance does Qemu accept .ISO files? I tried loading FreeBSD but I am getting the error from…
TEddyBEaR
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Understanding code block from XV6 makefile

I'm trying to understand the following code block from XV6 makefile : ULIB = ulib.o usys.o printf.o umalloc.o _%: %.o $(ULIB) $(LD) $(LDFLAGS) -N -e main -Ttext 0 -o $@ $^ $(OBJDUMP) -S $@ > $*.asm $(OBJDUMP) -t $@ | sed '1,/SYMBOL…
SyndicatorBBB
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Context Switching and Timer Interrupts in xv6

I am trying to modify the scheduling policy in xv6 in which Parent runs first after forking. childPid = fork(); if (childPid < 0) { printf("fork() is failed\n"); } else if (childPid == 0) // child { printf("…
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How to implement a system call that has structure parameter?

I want to implement a system call where I pass in a reference to a structure variable, then I would like display the values in the same file. For example I have the following structure. struct procInfo{ int processID[64]; // the PID of each…
Ammar
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When killing a process, can I use its' `eax` to save exit status?

I'm taking OS class and we need to extend XV6's exit() to support exit status, thus we're writing exit2(int). I thought of two candidates for the purpose of saving the exit status of the killed process. The first option was to add a variable to…
Quaker
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