* [metal] Copy program pages to extended memory at startup
* [metal] Reclaim base memory pages for later app use
* [metal] Load program pages beyond 1st 440 KiB to extended memory
o//examples/hellolua.com now runs correctly under QEMU (in
legacy BIOS mode).
* [metal] Place GDT in read/write segment
The CPU absolutely needs to alter the GDT when loading the
task register (via ltr). To account for this, I move the
GDT into a read/write data section. There is still a "rump"
read-only GDT in the text section that is used by the real
mode bootloader.
We also delay the loading of the task register (ltr) until
after the IDT and TSS are finally set up.
* [metal] Get examples/vga2.c serial output working for UEFI boot
* [metal] Get examples/vga2.c VGA output working for UEFI boot
* [metal] Allow munmap() to reclaim dynamically allocated pages
* Place TLS sections right after .text, not after embedded zip file
Co-authored-by: tkchia <tkchia-cosmo@gmx.com>
* [metal] Refactoring: separate out sys_writev_vga() and _vga_init() modules
* [metal] Read VGA info from BDA before long mode entry, not after
If using a pre-existing VGA text console, the VGA initialization
code now retrieves the cursor position & character height from
the BIOS data area while still in real mode — rather than
reading from the BIOS data area only after entering long mode.
(This should help make the code more correct, if Cosmopolitan
were to support UEFI graphics output in the future. If the
program were booted via UEFI, then the long mode IsMetal()
code would still be activated, but the BIOS data area might
not have been initialized in that case.)
This change also means that there are now a few more fields
in the `struct mman`.
* [metal] VGA console can now show "screen of death" upon a crash
There is now a new function _klog_vga(), which can be called
by kprintf() to output system messages — e.g. information about
CPU exceptions — on the VGA screen.
* [metal] CPU exception handler now dumps cr2 value
* [metal] Add demo of program crash reporting w/ bare metal VGA TTY
* [metal] Reduce size of "screen of death" code
