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2018-07-07Added '-g' flag for GCC to all makefiles to ensure debugging informationJake Mannens
is produced. This may change later. Added the new directory 'lib' to the source tree which build lib.a, an archive containing common library routines for both the kernel and userspace code to use. Added the file string.c to the lib directory (as well as the appropriate headers in /include) which provides some basic functions from the standard C string library. Added a physical memory manager which is now located in memory.c. This memory manager tracks free pages from 1MB-8MB with a simple table and allocates memory in blocks of 4KB pages. Multiple pages can be allocated in which they are returned as a linked list. Added a 'page window' in memory.c which allows the temporary mapping of a single page at a time into the current address space. Moved all paging routines that were previously located in page.s over to memory.c where they have been re-implemented as a mixture of C and inline assembly. Moved the primative userspace routines from usrspace.s over to the new sched.c. The only remaining routine, usrcall is now located in asm.s as 'switch_to' which takes two arguments, pointers to the task structure and task state structure of the new task which is being switched to. Pages for userspace are now allocated dynamically. The user binary is loaded in at 1GB upwards. The user stack is located at the end of the 4GB address space with the lower 1GB being reserved for the kernel. Updated the link.ld file for the userspace binary to include the new starting address 0x40000000 (1GB). Renamed the symbols for the user binary blob to make them shorter.
2018-06-25Added the header asm/interrupt.h which includes a prototype for theJake Mannens
assembly function register_isr making it usable within the C portions of the source. Added a new file panic.s with the function panic that will print a panic message, disable interrupts and halt the system. Created the skeleton framework for paging in the new file page.s. The new function paging_init (called in kboot) will setup a simple page directory with two tables covering all addresses 0-8MB. It will also mark pages from 0-1MB as 'supervisor-only' to protect the kernel. NOTE: The function paging_init must be called before initialising the IDT as it does not disable interrupts! Modified the page fault handler to print the offending linear address along with the supplied error code. Following that, the handler will initiate a kernel panic. This function (along with panic) assumes console I/O to be operational. Modified the userspace test code to deliberately intiate a page fault by accessing an unmapped page.
2018-06-16Initial commitJake Mannens