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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.
2018-06-23Re-wrote interrupt handling. Now, flush_idt only initializes IDT entriesJake Mannens
32-255. A separate routine in the new file traps.s initializes the first 32 entries with addresses pointing to exception handlers within said file. Modified the register_isr function to now accept a descriptor privilege level which it will assign to the modified IDT entry. Added a task state segment and corresponding entry to the GDT. The TSS will store the kernel's stack pointer and stack segment when switching to userspace. NOTE: The stack pointer MUST be saved manually before switching to userspace! Added the framework for a system call interface at interrupt vector 0x80 (128).
2018-06-20Added a very basic types.h header file that defines NULL, size_t andJake Mannens
time_t. Moved the kernel's loading point down to address 0 in conventional memory and updated linker scripts accordingly. Began to experiment with loading a binary blob into extended memory (0x100000), switching to userspace mode, and executing it.
2018-06-19Added foundation code to initialize the PIT and create a 10ms jiffiesJake Mannens
counter.
2018-06-16Initial commitJake Mannens