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I am doing the Pintos project on the side to learn more about operating systems. I had tons of devops trouble at first with it not running well on an 18.04 Ubuntu droplet. I am now running it on the VirtualBox image that UCCS tells students to download for pintos.

I finished project 1 and started to map out my solution to project 2. Following the instructions to create a file I ran 

pintos-mkdisk filesys.dsk --filesys-size=2
pintos -- -f -q

but am getting error 

Kernel PANIC at ../../threads/vaddr.h:87 in vtop(): assertion 
`is_kernel_vaddr (vaddr)' failed.

I then tried running make check (all the tests). They are all failing for the same reason.

Am I missing something? Is there something I need to implement to fix this? I reread the instructions and didnt see anything?

Would appreciate help! Thanks

Nate
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2 Answers2

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I had a similar problem. My code for Project 1 ran fine, but I could not format the filesystem for Project 2.

The failure for me came from the following call chain:

thread_init() -> ... -> thread_schedule_tail() -> process_activate() -> pagedir_activate() -> vtop()

The problem is that init_page_dir is still NULL when pagedir_activate() is called. init_page_dir should have been initialized in paging_init() but this is called after thread_init().

The root cause was that my scheduler was being called too early, i.e. before the call to thread_start(). The reason for my problem was that I had built in a call to thread_yield() upon completion of every call to lock_release() which makes sense from a priority donation standpoint. Unfortunately, locks are used prior to the scheduler being ready! To fix this, I installed a flag called threading_started that bails in the first line of my thread_block() and thread_yield() functions if thread_start() has not yet been called.

Good luck!

Charles Celerier
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  • This helped me find the answer! I was calling thread_yield() every time in sema_down(), the early preemption screwed everything up. Thanks! – Nate Oct 04 '18 at 02:18
  • Good luck with the next project! I just started working on supporting user programs yesterday. – Charles Celerier Oct 06 '18 at 10:17
  • Finished the project yet? :) Im working on filesystems right now, I added logic for extensible files and am just debugging. Great project. Thanks for the help early on. I gave you upvotes on both but It doesn't show since my account is new. Cheers – Nate Nov 20 '18 at 22:34
  • Oh geeze. I'm not a fan of the StackOverflow policies for new members, especially for these types of somewhat obscure questions. To answer your question, I finished supporting user programs, and now I'm working on virtual memory. It's taking me a bit to figure out how to get started, but I'll probably knock it out over the next few weekends. – Charles Celerier Nov 22 '18 at 20:00
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Additional to Charles Celerier's answer, this worked for me.

Define thread_try_yield such as

void thread_try_yield(void) {
  if (!list_empty(&ready_list) && thread_current() != idle_thread)
    thread_yield();
}

and call it rather than calling thread_yield() directly.

parkjbdev
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