When compiled with gcc 4.6.1, 32-bit Sortix would triple fault during
early boot: When the TLB is being flushed, somehow a garbage value had
sneaked into Sortix::Memory::currentdir, and a non-page aligned (and
garbage) page directory is loaded. (Triple fault, here we come!)
However, adding a volatile addr_t foo after the currentdir variable
actually caused the system to boot correctly - the garbage was written
into that variable instead. To debug the problem, I set the foo value
to 0: as long as !foo (hence the name nofoo) everything was alright.
After closer examination I found that the initrd open code wrote to a
pointer supplied by kernel.cpp. The element pointed to was on the
stack. Worse, its address was the same as currentdir (now foo).
Indeed, the stack had gone into the kernel's data segment!
Turns out that this gcc configuration stores variables in the data
segment in the reverse order they are defined in, whereas previous
compilers did the opposite. The hack used to set up the stack during
early boot relied on this (now obviously incorrect) fact.
In effect, the stack was initialized to the end of the stack, not
the start of it: completely ignoring all the nice stack space
allocated in kernel.cpp.
I did not see that one coming.
This commit fixes some instances of uninitialized memory.
In addition, the bootstrap tables for x64 are moved around a bit,
in this awful game of placing stuff where it won't collide with grub.
Made FILE an interface to various backends. This allows application writers
to override the standard FILE API functions with their own backends. This
is highly unportable - it'd be nice if a real standard existed for this.
glibc already does something like this internally, but AFAIK you can't hook
into it.
Added fdopen(3), fopen(3), fregister(3), funregister(3), fread(3),
fwrite(3), fseek(3), clearerr(3), ferror(3), feof(3), rewind(3), ftell(3),
fflush(3), fclose(3), fileno(3), fnewline(3), fcloseall(3), memset(3),
stdio(3), vfprintf(3), fprintf(3), and vprintf(3).
Added a file-descriptor backend to the FILE API.
fd's {0, 1, 2} are now initialized as stdin, stdout, and stderr when the
standard library initializes.
fcloseall(3) is now called on exit(3).
decl/intn_t_.h now @include(size_t.h) instead of declaring it itself.
Added <stdint.h>.
The following programs now flush stdout: cat(1), clear(1), editor(1),
init(1), mxsh(1).
printf(3) is now hooked up against vprintf(3), while Maxsi::PrintF
remains using the system call, for now.
This lets the kernel use any memory not directly used by it or the
init ramdisk. Although, now we test whether the kernel fits into
the identitymapped area. It can't really grow down there, unless it
wants to collide with user-space. Instead, modules and the like
(when they are invented), should be put in the upper memory. Or in
their own user-space process, yay, microkernel!
This fixes issues where it did not fit into the first few MiB,
or that GRUB loaded it someplace weird.
The kernel heap is now also protected against growing into the
ramdisk and the kernel stack.
Jonas 'Sortie' Termansen
Steve Dougherty