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2019-05-31fork/wait/exit workRobert Morris1-6/+5
2018-09-23Checkpoint port of xv6 to x86-64. Passed usertests on 2 processors a few times.Frans Kaashoek1-1/+1
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
2016-08-25Remove trailing white space with:Frans Kaashoek1-3/+3
for f in *.{h,c}; do sed -i .sed 's/[[:blank:]]*$//' $f; done (Thanks to Nicolás Wolovick)
2011-09-01Use stosl in memset; makes boot time bearableAustin Clements1-1/+5
2009-10-07Remove memcpy prototypes at Russ' request to prevent code from callingAustin Clements1-0/+1
memcpy directly.
2009-10-07Provide memcpy for compatibility with older versions of gccAustin Clements1-0/+6
2009-03-08xv6: use stosb for memsetrsc1-6/+2
2007-08-28spaces around else for rtmrsc1-1/+1
2007-08-28more consistent spacingrsc1-3/+3
2007-08-27delete unnecessary #include linesrsc1-1/+0
2007-08-24first ever correct use of strncpyrsc1-2/+14
2007-08-21Various cleanup:rsc1-0/+10
- Got rid of dummy proc[0]. Now proc[0] is init. - Added initcode.S to exec /init, so that /init is just a regular binary. - Moved exec out of sysfile to exec.c - Moved code dealing with fs guts (like struct inode) from sysfile.c to fs.c. Code dealing with system call arguments stays in sysfile.c - Refactored directory routines in fs.c; should be simpler. - Changed iget to return *unlocked* inode structure. This solves the lookup-then-use race in namei without introducing deadlocks. It also enabled getting rid of the dummy proc[0].
2007-08-10avoid assignments in declarationsrsc1-5/+7
2007-08-08add safestrcpyrsc1-0/+16
2006-09-06standardize various * conventionsrsc1-12/+12
2006-09-06spacing fixes: no tabs, 2-space indents (for rtm)rsc1-7/+7
2006-08-30complain if no disk 1rtm1-18/+0
lots of cleanup
2006-07-20uint32_t -> uint &crtm1-3/+3
2006-07-17add uint and standardize on typedefs instead of unsignedrsc1-6/+6
2006-07-16Attempt to clean up newproc somewhat.rsc1-12/+18
Also remove all calls to memcpy in favor of memmove, which has defined semantics when the ranges overlap. The fact that memcpy was working in console.c to scroll the screen is not guaranteed by all implementations.
2006-07-05timer interruptskaashoek1-0/+11
disk interrupts (assuming bochs has a bug)
2006-06-22checkpoint. booting second processor. stack is messed up, but thanks to cliffkaashoek1-0/+20
and plan 9 code, at least boots and gets into C code.
2006-06-21start on MP; detect MP configurationkaashoek1-0/+15
2006-06-15primitive fork and exit system callsrtm1-0/+3
2006-06-12importrtm1-0/+22