X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=TODO;h=522847aa1dc88f2a95d36d3a0f193c13ec8353c8;hb=a94b142a7aa0866a03dd7cc89ee5a9b366377a63;hp=45b06ce068a72522a5acfd87cca5ec3f99304832;hpb=74a79e1f43c2b58eaf32a5d562d94d15abbbb2bb;p=pintos-anon diff --git a/TODO b/TODO index 45b06ce..522847a 100644 --- a/TODO +++ b/TODO @@ -1,7 +1,5 @@ -*- text -*- -* Bochs is not fully reproducible. - Godmar says: - In Project 2, we're missing tests that pass arguments to system calls @@ -103,38 +101,6 @@ I actually tested it and it's hard to pass with the current ips setting. The bounds on how quickly a thread would need to be able to return after sleep appear too tight. Need another idea. -From: "Godmar Back" -Subject: thread_yield in irq handler -To: "Ben Pfaff" -Date: Wed, 22 Feb 2006 22:18:50 -0500 - -Ben, - -you write in your Tour of Pintos: - -"Second, an interrupt handler must not call any function that can -sleep, which rules out thread_yield(), lock_acquire(), and many -others. This is because external interrupts use space on the stack of -the kernel thread that was running at the time the interrupt occurred. -If the interrupt handler tried to sleep and that thread resumed, then -the two uses of the single stack would interfere, which cannot be -allowed." - -Is the last sentence really true? - -I thought the reason that you couldn't sleep is that you would put -effectively a random thread/process to sleep, but I don't think it -would cause problems with the kernel stack. After all, it doesn't -cause this problem if you call thread_yield at the end of -intr_handler(), so why would it cause this problem earlier. - -As for thread_yield(), my understanding is that the reason it's called -at the end is to ensure it's done after the interrupt is acknowledged, -which you can't do until the end because Pintos doesn't handle nested -interrupts. - - - Godmar - From: "Godmar Back" For reasons I don't currently understand, some of our students seem @@ -237,32 +203,15 @@ Godmar Back writes: * 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). -* lock_acquire(), lock_release() don't need additional intr_dis/enable - calls, because the semaphore protects lock->holder. - [ Think this over: is this really true when priority donation is - implemented? intr_dis/enable prevents the race with thread_set_priority. - Leaving it there could help the students getting the correct synchronization - right. - ] - - - * process_death test needs improvement * Internal tests. @@ -309,3 +258,66 @@ via Godmar Back: . 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.