Upgrade to GRUB2

[perlun]

Let's face it: grub-legacy is, after all, legacy. GRUB 2 was released 6 years ago at the time of writing (June 2012). We should adopt these new changes.

There are a few steps involved:

• [x] Create a grub.cfg file using the new syntax. Done in 01b373d74910acd0b6b3db0e3b9b6d3f05c8a5e6
• [x] Fix exception on startup below. Done in acb8b52c9a59b8b516f1f6811fb2d935ccdfc115.

• [x] Fix weirdness with ipc_receive with mailbox_receive calls being messed up. Some form of evil race condition, not managed to find the root cause even after many hours of debugging. Finally managed to find and fix this in #124. The text below was written while working on the fix and is kept for historical purposes.
  • Reproduced with grub-legacy also: https://github.com/chaos4ever/chaos/compare/grub-1-reproducing-mailbox-receive-bug
  • Minimal GRUB 2 change still reproduces it: https://github.com/chaos4ever/chaos/compare/master...grub2-minimal (sometimes works, sometimes generates GPF)
  • Verified that physical pages for stack pages in different threads are not the same (i.e. it shouldn't be as easy as virtual page -> physical page mapping is identical, and one thread is overwriting another thread)
  • Seems somewhat timing related: when adding trace/breakpoints in GDB, the exact thread that runs into the issue can differ, as well as the mailbox ID of the failing mailbox. Just to be on the same side, I added a dummy stack variable which would be incremented in the while (TRUE) loop inside handle_connection - the value in this variable was thread-local, as it ought to be according to the design.
  • Tried compiling with -O3 instead of -O0 as before - negative, doesn't change a dime.
  • Tried other things as well.
  • Found the issue. 🎉 More details in #124 and http://perlun.eu.org/en/2018/10/19/gdb-tracepoints
• [x] Change from using genisoimage to build our bootable ISO image and use grub-mkrescue instead. This should allow us to generate hybrid ISO/USB bootable images, making it possible to boot either as a CD ISO or by burning the ISO to a USB flash drive - this can be really useful if you want to run chaos on physical hardware. This part is done, but not merged since it revealed the error below.
• [ ] Optional: Update the kernel to use the Multiboot 2 specification (GRUB 2 still supports Multiboot version 1) Will likely not happen until we must do it, since Multiboot 1 works rather well.

[perlun]

More info on startup exception: fired up qemu -s and attached a gdb, placed a breakpoint on the failing line (the error was reproducible in QEMU also). Managed to see the kernel output before the crash:

                  Starting (null)
                   (process ID 0).
                  storm 0.5.1+ booting...
                  Compiled by per@ceres-debian on Sep 28 2018 22:32:36 (revision 4931669).
                  Machine: Celeron (Mendocino) at 950373170 Hz (~950 MHz).
                  Memory: Total 511 MB, kernel 23672 KB, reserved 384 KB, free 500104 KB.
                  VM subsystem initialized.
                  Global memory initialized.
                  ISA-based I/O initialized.
                  DMA initialized.
                  IPC initialized.
                  Thread subsystem initialized.
                  Process subsystem initialized.
                  Started  (process ID 1).
                  Started  (process ID 2).
                  Started  (process ID 3).
                  Started  (process ID 4).
                  Started  (process ID 5).
                  Started  (process ID 6).
                  Started  (process ID 7).
                  Started  (process ID 8).
                  Started  (process ID 9).
                  Started  (process ID 10).
                  Started  (process ID 11).

The missing process names is an indication that some of the Multiboot info is not being passed from the GRUB 2 bootloader to the kernel as expected.