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2018-09-23Checkpoint port of xv6 to x86-64. Passed usertests on 2 processors a few times.Frans Kaashoek39-773/+1050
The x86-64 doesn't just add two levels to page tables to support 64 bit addresses, but is a different processor. For example, calling conventions, system calls, and segmentation are different from 32-bit x86. Segmentation is basically gone, but gs/fs in combination with MSRs can be used to hold a per-core pointer. In general, x86-64 is more straightforward than 32-bit x86. The port uses code from sv6 and the xv6 "rsc-amd64" branch. A summary of the changes is as follows: - Booting: switch to grub instead of xv6's bootloader (pass -kernel to qemu), because xv6's boot loader doesn't understand 64bit ELF files. And, we don't care anymore about booting. - Makefile: use -m64 instead of -m32 flag for gcc, delete boot loader, xv6.img, bochs, and memfs. For now dont' use -O2, since usertests with -O2 is bigger than MAXFILE! - Update gdb.tmpl to be for i386 or x86-64 - Console/printf: use stdarg.h and treat 64-bit addresses different from ints (32-bit) - Update elfhdr to be 64 bit - entry.S/entryother.S: add code to switch to 64-bit mode: build a simple page table in 32-bit mode before switching to 64-bit mode, share code for entering boot processor and APs, and tweak boot gdt. The boot gdt is the gdt that the kernel proper also uses. (In 64-bit mode, the gdt/segmentation and task state mostly disappear.) - exec.c: fix passing argv (64-bit now instead of 32-bit). - initcode.c: use syscall instead of int. - kernel.ld: load kernel very high, in top terabyte. 64 bits is a lot of address space! - proc.c: initial return is through new syscall path instead of trapret. - proc.h: update struct cpu to have some scratch space since syscall saves less state than int, update struct context to reflect x86-64 calling conventions. - swtch: simplify for x86-64 calling conventions. - syscall: add fetcharg to handle x86-64 calling convetions (6 arguments are passed through registers), and fetchaddr to read a 64-bit value from user space. - sysfile: update to handle pointers from user space (e.g., sys_exec), which are 64 bits. - trap.c: no special trap vector for sys calls, because x86-64 has a different plan for system calls. - trapasm: one plan for syscalls and one plan for traps (interrupt and exceptions). On x86-64, the kernel is responsible for switching user/kernel stacks. To do, xv6 keeps some scratch space in the cpu structure, and uses MSR GS_KERN_BASE to point to the core's cpu structure (using swapgs). - types.h: add uint64, and change pde_t to uint64 - usertests: exit() when fork fails, which helped in tracking down one of the bugs in the switch from 32-bit to 64-bit - vectors: update to make them 64 bits - vm.c: use bootgdt in kernel too, program MSRs for syscalls and core-local state (for swapgs), walk 4 levels in walkpgdir, add DEVSPACETOP, use task segment to set kernel stack for interrupts (but simpler than in 32-bit mode), add an extra argument to freevm (size of user part of address space) to avoid checking all entries till KERNBASE (there are MANY TB before the top 1TB). - x86: update trapframe to have 64-bit entries, which is what the processor pushes on syscalls and traps. simplify lgdt and lidt, using struct desctr, which needs the gcc directives packed and aligned. TODO: - use int32 instead of int? - simplify curproc(). xv6 has per-cpu state again, but this time it must have it. - avoid repetition in walkpgdir - fix validateint() in usertests.c - fix bugs (e.g., observed one a case of entering kernel with invalid gs or proc
2018-09-02Update nameFrans Kaashoek1-3/+3
Use generic 6.828 url (without year)
2018-08-31thanks tyfkdaFrans Kaashoek4-19/+20
2018-08-31thanks Wolfgang KellerFrans Kaashoek1-1/+1
2018-08-30xFrans Kaashoek1-1/+1
2018-08-30Allow holding to be called with interrupts enabled (for Mark Morrissey).Frans Kaashoek1-1/+5
2018-08-30Delete a patchFrans Kaashoek3-154/+4
Adjust typesetting of code
2018-08-30xFrans Kaashoek1-3/+6
2018-08-30xFrans Kaashoek1-8/+9
2018-08-30thanks mtasmFrans Kaashoek3-2/+10
2018-08-30thanks wxdaoFrans Kaashoek1-2/+2
2018-08-30thanks eyalz800Frans Kaashoek2-2/+2
2018-08-30vectors.pl is executable and asks shell for perlFrans Kaashoek1-1/+2
2018-08-30thanks matanessFrans Kaashoek1-1/+3
2018-08-30thanks tyfkdaFrans Kaashoek1-2/+2
2018-08-30xFrans Kaashoek1-1/+1
2018-08-30Remove unused flags (thanks Wolfgang Keller)Frans Kaashoek2-50/+4
2018-08-30xFrans Kaashoek1-1/+1
2018-08-30xFrans Kaashoek1-4/+4
2018-08-30Because sleeplocks replaced B_BUSY the holding test canFrans Kaashoek1-1/+1
be more specific (thanks Mark Morrissey)
2018-08-30xFrans Kaashoek1-1/+0
2017-10-24stricter log consumption by write()Robert Morris1-1/+1
2017-10-08improve swtch commentRobert Morris1-2/+3
2017-08-29fix runoff complaints about pagination and long linesRobert Morris11-33/+25
2017-08-10thxFrans Kaashoek1-6/+8
2017-08-09Update comment to reflect xv6 doesn't have per-cpu segments anymoreFrans Kaashoek1-1/+1
2017-08-09nothing muchRobert Morris3-3/+5
2017-08-09Commit to running on an SMP (perhaps with only 1 core). Remove most codeFrans Kaashoek10-125/+6
from picirq.c and remove timer.c completely. Update runoff.list.
2017-08-09comment fixesRobert Morris2-9/+12
2017-08-08Thanks Anton Burtsev <[email protected]>Frans Kaashoek1-0/+1
2017-08-08fix iput() to more obviously avoid deadlockRobert Morris1-7/+9
2017-08-08a little more lock documentationRobert Morris1-0/+13
2017-08-08protect ip->valid and ip->nlink with sleep lock in iput()Robert Morris2-10/+12
2017-08-08change ip->flags&I_VALID to ip->validRobert Morris2-12/+11
2017-08-08Merge branch 'master' of g.csail.mit.edu:xv6-devRobert Morris19-172/+181
2017-08-08frans' fixes to iput()Robert Morris1-0/+2
2017-08-08fs comment nitsRobert Morris1-7/+7
2017-08-07Remove some debugging statementsFrans Kaashoek1-7/+0
2017-08-07Merge branch 'nogs'Frans Kaashoek19-165/+181
2017-08-07Merge branch 'patch-1' of https://github.com/aliceinwire/xv6-publicFrans Kaashoek1-1/+1
2017-08-07Merge branch 'patch-1' of https://github.com/Saarett/xv6-publicFrans Kaashoek1-1/+3
2017-04-26Fix typo in dirlookupGrant Wu1-1/+1
2017-02-27Update LICENSEAlice Ferrazzi1-1/+1
updated copyright year
2017-02-05Free pgdir in setupkvm in case of mappages failureSaarett1-1/+3
There is a potential memory leak when mappages() fails inside setupkvm(). A call to freevm() is added in this case so as to reclaim the lost mapping pages.
2017-02-01A tiny bit of clean up (e.g., move code searching cpu array from lapic.c intoFrans Kaashoek4-17/+17
mycpu() in proc.c.
2017-02-01use panicFrans Kaashoek2-7/+4
2017-02-01shorten commentFrans Kaashoek1-6/+2
2017-02-01Eliminate code for gs trick to track per-cpu state. We rely on lapiccpunum()Frans Kaashoek8-67/+33
to find a per-cpu id with which we locate a cpu's cpu struct.
2017-01-31Read curproc from cpu structure, but be careful because after a schedule eventFrans Kaashoek7-62/+97
myproc() points to a different thread. myproc(); sched(); myproc(); // this proc maybe different than the one before sched Thus, in a function that operates on one thread better to retrieve the current process once at the start of the function.
2017-01-31Start of an experiment to remove the use of gs for cpu local variables.Frans Kaashoek17-123/+145
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