X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=TODO;h=38836157fc052fe3a07b91d5d03bea94c64ac104;hb=40b003737f5c103cecd7c09f5fc2970907e222a5;hp=bb96b8825e807c5694453c3b222149a24ede4ca6;hpb=72e077d7a5880e21a753a8d8d1eeb8df2cc39f70;p=pintos-anon diff --git a/TODO b/TODO index bb96b88..3883615 100644 --- a/TODO +++ b/TODO @@ -1,27 +1,25 @@ -*- text -*- -From: Godmar Back -Subject: project 4 question/comment regarding caching inode data -To: Ben Pfaff -Date: Sat, 14 Jan 2006 15:59:33 -0500 - -Ben, - -in section 6.3.3 in the P4 FAQ, you write: - -"You can store a pointer to inode data in struct inode, if you want," - -Should you point out that if they indeed do that, they likely wouldn't -be able to support more than 64 open inodes systemwide at any given -point in time. - -(This seems like a rather strong limitation; do your current tests -open more than 64 files? -It would also point to an obvious way to make the projects harder by -specifically disallowing that inode data be locked in memory during -the entire time an inode is kept open.) - - - Godmar +Godmar says: + +- In Project 2, we're missing tests that pass arguments to system calls +that span multiple pages, where some are mapped and some are not. +An implementation that only checks the first page, rather than all pages +that can be touched during a call to read()/write() passes all tests. + +- Need some tests that test that illegal accesses lead to process +termination. I have written some, will add them. In P2, obviously, +this would require that the students break this functionality since +the page directory is initialized for them, still it would be good +to have. + +- There does not appear to be a test that checks that they close all +fd's on exit. Idea: add statistics & self-diagnostics code to palloc.c +and malloc.c. Self-diagnostics code could be used for debugging. +The statistics code would report how much kernel memory is free. +Add a system call "get_kernel_memory_information". User programs +could engage in a variety of activities and notice leaks by checking +the kernel memory statistics. From: Godmar Back Subject: on caching in project 4 @@ -57,57 +55,25 @@ the same performance, which raises the suspicion that the test workload might not force any cache replacement, so the eviction strategy doesn't matter.) -Godmar Back writes: - -> in your sample solution to P4, dir_reopen does not take any locks when -> changing a directory's open_cnt. This looks like a race condition to -> me, considering that dir_reopen is called from execute_process without -> any filesystem locks held. - * Get rid of rox--causes more trouble than it's worth * Reconsider command line arg style--confuses everyone. * Finish writing tour. -* Introduce a "yield" system call to speed up the syn-* tests. - via Godmar Back: -* Project 3 solution needs FS lock. - * Get rid of mmap syscall, add sbrk. -* Make backtrace program accept multiple object file arguments, - e.g. add -u option to allow backtracing user program also. - * page-linear, page-shuffle VM tests do not use enough memory to force eviction. Should increase memory consumption. * Add FS persistence test(s). - - - - * process_death test needs improvement * Internal tests. -* Improve automatic interpretation of exception messages. - -* Userprog project: - - - Mark read-only pages as actually read-only in the page table. Or, - since this was consistently rated as the easiest project by the - students, require them to do it. - - - Don't provide per-process pagedir implementation but only - single-process implementation and require students to implement - the separation? This project was rated as the easiest after all. - Alternately we could just remove the synchronization on pid - selection and check that students fix it. - * Filesys project: - Need a better way to measure performance improvement of buffer @@ -127,12 +93,71 @@ via Godmar Back: - Add extra credit: - . Low-level x86 stuff, like paged page tables. - . Specifics on how to implement sbrk, malloc. . Other good ideas. - . opendir/readdir/closedir - . everything needed for getcwd() + +To add partition support: + +- Find four partition types that are more or less unused and choose to + use them for Pintos. (This is implemented.) + +- Bootloader reads partition tables of all BIOS devices to find the + first that has the "Pintos kernel" partition type. (This is + implemented.) Ideally the bootloader would make sure there is + exactly one such partition, but I didn't implement that yet. + +- Bootloader reads kernel into memory at 1 MB using BIOS calls. (This + is implemented.) + +- Kernel arguments have to go into a separate sector because the + bootloader is otherwise too big to fit now? (I don't recall if I + did anything about this.) + +- Kernel at boot also scans partition tables of all the disks it can + find to find the ones with the four Pintos partition types (perhaps + not all exist). After that, it makes them available to the rest of + the kernel (and doesn't allow access to other devices, for safety). + +- "pintos" and "pintos-mkdisk" need to write a partition table to the + disks that they create. "pintos-mkdisk" will need to take a new + parameter specifying the type. (I might have partially implemented + this, don't remember.) + +- "pintos" should insist on finding a partition header on disks handed + to it, for safety. + +- Need some way for "pintos" to assemble multiple disks or partitions + into a single image that can be copied directly to a USB block + device. (I don't know whether I came up with a good solution yet or + not, or whether I implemented any of it.) + +To add USB support: + +- Needs to be able to scan PCI bus for UHCI controller. (I + implemented this partially.) + +- May want to be able to initialize USB controllers over CardBus + bridges. I don't know whether this requires additional work or if + it's useful enough to warrant extra work. (It's of special interest + for me because I have a laptop that only has USB via CardBus.) + +- There are many protocol layers involved: SCSI over USB-Mass Storage + over USB over UHCI over PCI. (I may be forgetting one.) I don't + know yet whether it's best to separate the layers or to merge (some + of) them. I think that a simple and clean organization should be a + priority. + +- VMware can likely be used for testing because it can expose host USB + devices as guest USB devices. This is safer and more convenient + than using real hardware for testing. + +- Should test with a variety of USB keychain devices because there + seems to be wide variation among them, especially in the SCSI + protocols they support. Should try to use a "lowest-common + denominator" SCSI protocol if any such thing really exists. + +- Might want to add a feature whereby kernel arguments can be given + interactively, rather than passed on-disk. Needs some though.