diff options
Diffstat (limited to 'documentation')
| -rw-r--r-- | documentation/memory.txt | 17 | ||||
| -rw-r--r-- | documentation/syscalls.txt | 27 |
2 files changed, 39 insertions, 5 deletions
diff --git a/documentation/memory.txt b/documentation/memory.txt index e820034..581bd71 100644 --- a/documentation/memory.txt +++ b/documentation/memory.txt @@ -1,7 +1,14 @@ only the first 32GiB of physical memory are considered. this can be changed -with pram_pages in paging.cpp. as for virtual memory, the top 1GiB is reserved -for the kernel. the top 1MiB of that is reserved for the kernel stack, with an -unmapped guard page at the top and bottom of the kernel stack. +with pram_pages in paging.cpp. vram layout is as follows: -if any of these facts change, the linker script and paging code should be -checked closely. +0x0000.0000.0000 - 0x0000.001f.ffff: always unmapped +0x0000.0020.0000 - 0x0000.3fbf.ffff: available to user process +0x0000.3fc0.0000 - 0x0000.3fdf.ffff: always unmapped +0x0000.3fe0.0000 - 0x0000.3fff.ffff: user stack +0x0000.4000.0000 - 0xffff.bfff.ffff: always unmapped +0xffff.c000.0000 - 0xffff.ffdf.ffff: available to kernel +0xffff.ffe0.0000 - 0xffff.ffe0.0fff: always unmapped +0xffff.ffe0.1000 - 0xffff.ffef.efff: interrupt stack +0xffff.ffef.f000 - 0xffff.fff0.0fff: always unmapped +0xffff.fff0.1000 - 0xffff.ffff.efff: syscall stack / kernel init stack +0xffff.ffff.f000 - 0xffff.ffff.ffff: always unmapped diff --git a/documentation/syscalls.txt b/documentation/syscalls.txt new file mode 100644 index 0000000..cbba5e3 --- /dev/null +++ b/documentation/syscalls.txt @@ -0,0 +1,27 @@ +on application entry: + there is a 1MiB - 8KiB area mapped writable and not + executable with guard pages on either side, and rsp is + set to the top of that. all other registers are set to 0. + +for all system calls: + rax, rdi, rsi, rdx are in/out paramters. + rbx, rbp, rsp, r12-r15 are preserved. + rcx, rflags, r8-r11 are clobbered. + +encode color: + rax in: 0 + edi in: r + g * 256 + b * 65536 + eax out: encoded color + +get framebuffer: + rax in: 1 + rax out: pointer to framebuffer + rdi out: width + height * 2 ** 32 + esi out: pitch + framebuffer is always 32 bpp. use the encode color syscall + to encode colors. pitch is in dwords, not in bytes. + +draw framebuffer: + rax in: 2 + this draws changes to the framebuffer gotten by the get framebuffer + system call. (currently, the entire thing is copied, not just changes.) |