Changes

1.7.0 - DD-MMM-2025
===================
- Added the member s_blocksize_bits in the superblock struct to use bitwise
  shift instead of division in ext2_bmap() and ext2_truncate().
- Changed modulo operations by bitwise (where possible) to reduce dependency
  from libgcc.
- Removed some flags from LDFLAGS in the main Makefile that prevented compile
  the kernel with newer GCC versions. [#97]
- Fixed ext2_balloc() and ext2_ialloc() to return -ENOSPC when there is not
  space on device.
- Fixed fs.h to include fd.h when CONFIG_NET is not set.
- Fixed some kernel crashes with the message 'WARNING: page_head returned NULL!
  (free_pages = 0)' when using a RAMdisk drive as the root filesystem. [#98]


1.6.0 - 15-Nov-2024
===================
- Added support for UNIX-domain sockets (with the Berkeley socket API). [#36]
- Added support for sys_truncate64, sys_ftruncate64, sys_stat64, sys_lstat64,
  sys_fstat64 and sys_fcntl64 system calls. [#49]
- Added support for sys_getdents64. [#51]
- Added support for sys_chown32. [#53]
- Added support for sys_utimes. [#57]
- Added support for building Fiwix with the TCC compiler. [#63]
- Added support for the Linux boot protocol in kexec. [#65]
- Added support for the PS/2 mouse with the new device /dev/psaux. [#94]
- Added the new configuration option PAGE_HASH_PERCENTAGE (0.1% by default) to
  set the size of the page_hash_table relative to the number of physical memory
  pages, with a mininum of 1 page and a maximum of 16 pages. The kernel now
  shows the hash tables sizes during the boot.
- Added to sync drives when kernel stops because no more user processes exist.
  [#70]
- Added the flag PF_NOTINTERRUPT to avoid waking up a process sleeping in the
  non-interruptible mode.
- Added a consistency check on every directory entry during ext2_lookup().
- Added a call to invalidate_buffers() before reread the partition table in the
  ioctl BLKRRPART.
- Rewritten how multiple I/O block requests are managed. Now the new I/O block
  layer enqueues a block request group with all the buffers needed in a read or
  write operation, and keeps sleeping until the whole transaction has been
  completed. This improves dramatically the disk accesses, reduces a lot the
  number of context switches, and it overall boosts the performance of the
  system.
- Changed the file position for reads to be set to zero when a file is opened
  with O_APPEND. [#76]
- Implement mapping framebuffer physical address to user space using mmap. [#79]
- Changed the inode cache mechanism to avoid caching inodes from
  pseudo-filesystems.
- Changed count_active_procs() to also count processes that are sleeping as
  non-interruptible.
- Changed the tty sleeping address to be process specific in order to reduce
  the wakeup latency.
- Moved the values sb->dirty, inode->locked and inode->dirty to flags.
- Moved the call to sysrq() into the keyboard interrupt bottom half.
- Improved code compaction and efficiency in ATA disk read/write.
- Improved the efficiency of the buffer cache.
- Improved ext2_file_write() to use a multiblock request with gbread() when the
  count is greater than the blocksize.
- Reorganized and improved the system console related code.
- Pass through 64-bit PAE memory entries as part of kexec. [#67]
- Make sure that the early system log will be shown in all system consoles.
- Removed unneeded low memory kernel virtual address mappings. [#88]
- Reduced a number of functions in the timer interrupt by moving them to the
  bottom half.
- Reorganized the code of the keyboard driver.
- Renamed and reorganized tty_queue into charq to make it more generic.
- Fixed sys_mount() to avoid mounting a device already mounted.
- Fixed compilation errors when CONFIG_PCI is not defined.
- Fixed to allow removing a directory in use. [#59]
- Fixed in sys_getcwd() to check 'diff_dev' variable before accessing
  'tmp_inode'. [#61]
- Fixed vconsole_select() to not switch to an unexistent vconsole.
- Fixed ata_hd_init() to make sure that the command SET_FEATURES is sent in all
  cases.
- Fixed the kernel stack backtrace to skip the first 5 stack values.
- Fixed an scrolling bug with 'vi' in fbcon_scroll_screen(). [#81]
- Fixed UNIX sockets working with select(). [#83]
- Fixed serial system console table overindex. [#87]
- Fixed a major problem in do_switch routine. [#89]
- Fixed incorrect passing of e820 memory map to Linux kexec guests. [#72]
- Fixed EXT2_DESC_PER_BLOCK() to avoid redundant calculations.
- Fixed kswapd() to enable interrupts after initializing devices.
- Fixed a long standing bug during bitmap calculation in the ext2 filesystem.
- Fixed CHECK_IF_NESTED_INTERRUPT by comparing KERNEL_CS against CS.
- Fixed a kernel crash on boot when PCI is disabled and the kernel parameter
  'bga=' is supplied.
- Fixed sleep() to avoid race conditions by executing CLI() earlier.
- Fixed a bug introduced in 4317cbe that prevented from continuing to the next
  running process in stop_kernel().
- Fixed read_msdos_partition() to use the default device block size instead of
  BLKSIZE_1K.
- Fixed to flag the superblock as dirty in ext2_ialloc(), ext2_ifree(),
  ext2_balloc() and ext2_bfree().
- Fixed fbcon_blank_screen() to not show cursor. [#94]
- Fixed a lack of schedule randomization introduced in b935b3d.
- Fixed reclaim_buffers() to run with interrupts enabled.
- Fixed to initialize the new vma struct in merge_vma_regions().
- Fixed to reset the flag before calling some functions to avoid reentrancy
  in irq_keyboard_bh().
- Fixed a long standing bug in vconsole_select() that prevented from switching
  between consoles in VT_PROCESS mode.
- Fixed permissions in the ioctl VT_WAITACTIVE.
- Fixed a long standing bug in wakeup() that put as running one in two processes
  sleeping, leading to frequent cases where some processes keep sleeping.
- Small fixes and cosmetic changes.


1.5.0 - 15-Nov-2023
===================
- Added a kernel memory allocator that uses the buddy algorithm to manage
  requests smaller than PAGE_SIZE (4KiB).
- Added the new file /proc/buddyinfo to view buddy algorithm statistics.
- Added the new configuration option FREE_PAGES_RATIO (with a default value of
  5), as the minimum percentage of free memory pages before calling the swapper
  to reclaim memory from the buffer cache.
- Added the buffer-dirty-flush kernel daemon 'kbdflushd'. This also includes the
  new configuration option BUFFER_DIRTY_RATIO to limit the percentage of dirty
  buffers.
- Added the new file '/proc/sys/vm/dirty_background_ratio' to show the current
  value of the option BUFFER_DIRTY_RATIO.
- Added support for the Bochs Graphics Adapter with the configuration option
  CONFIG_BGA, and introducing the new kernel parameter 'bga=' to set the screen
  resolution (width x height x bpp). Refer to 'docs/kernel-parameters.txt' to
  know all the screen resolutions supported.
- Added 32bit I/O transfers support to the ATA/ATAPI driver.
- Added DMA (Multi-word) transfers support to the ATA disk driver.
- Added overall improvements in the ATA disk driver.
- Added a check in psig() to terminate the process if it doesn't have the stack
  region in its vma table.
- Added PCI BARs handling in the serial driver.
- Added the files 'buffer_max' and 'buffer_nr' in '/proc/sys/kernel/'.
- Added more checks on data received during ATA drive identify to make sure it
  makes sense.
- Added the magic SysRq key 'm' to show current memory information.
- Added the Multiboot magic value as a new parameter in get_last_boot_addr() to
  avoid a kernel panic when it is booted without the Multiboot structure.
- Added a check if flag MULTIBOOT_INFO_ELF_SHDR is set before reading the ELF
  section header table to avoid possible kernel panics.
- Added support in parse_cmdline() to recognize values enclosed in double
  quotes.
- Added support for multiple RAMdisk drives.
- Added kexec implementation (see 'docs/kexec.txt') which introduces the new
  configuration option CONFIG_KEXEC (disabled by default).
- Added microsecond resolution to sys_gettimeofday().
- Added the /proc/<PID>/fd/ subdirectory containing symbolic links named by its
  file descriptor.
- Added support for 64bit offsets and introduced the new option CONFIG_OFFSET64
  (enabled by default).
- Added the linkage of libgcc into the kernel in order to have functions like
  __divdi3() and friends, necessary when doing certain arithmetic operations
  with 64bit offsets on an i386 architecture.
- Added support for the O_DIRECTORY flag to sys_open(). [#32]
- Added support for the virtual memory split 2GiB(user)/2GiB(kernel), by
  introducing the new option CONFIG_VM_SPLIT22 (disabled by default). [#34]
- Added support for large initrd images (see 'docs/initrd.txt'). [#34]
- Added the ability to have different blksize values for each device minor.
- Added the new system call sys_lchown by renaming the old sys_chown (number 16)
  to sys_lchown, and creating the new sys_chown (number 182) which will follow
  (dereference) symbolic links. This might break the compatibility with Linux
  2.0 ABI.
- Added support for F_DUPFD_CLOEXEC in sys/fcntl.h. [#40]
- Added support for sys_readv() and sys_writev() system calls. [#42]
- Added support for sys_mmap2() system call. [#47]
- Added the length modifier 'l' for long long int arguments in printk().
- Changed the mode how the kernel mounts the root filesystem. From now on, it
  will be mounted in read/write mode by default. This introduces the new kernel
  parameter 'ro' to force to mount it in read-only mode.
- Changed the vma table from static to dynamically allocated array and removed
  the option VMA_REGIONS.
- Changed lots of fixed-size arrays to dynamically allocated arrays.
- Changed malloc_name() and free_name() to use the new memory allocator.
- Changed do_namei() to use the new memory allocator.
- Changed the generic llseek() method to support 64bit offsets.
- Changed the location of the kernel stack address to be right after the BSS
  section. [#34]
- Rewritten reclaim_buffers() to be more efficient and also to free up unused
  buffers and shrink the buffer table.
- Modified the Makefile to disable compiling with PIE option enabled by some
  builds of GCC. [#6]
- Reverted 40bf18b because some signals weren't caugth and created malfunction
  in cron jobs.
- Reverted 082b316 as it created a kernel panic when using IPC shared memory.
- Reverted ad3fc56 so malloc_name() and free_name() will always request
  PAGE_SIZE bytes. This is more efficient as it helped to remove the call to
  strlen() and even can return now a proper ENAMETOOLONG error.
- Disabled interrupts in runnable() and not_runnable() to avoid race conditions.
- Removed the option RAMDISK_MAXSIZE from the RAMdisk drives.
- Bar addresses of PCI devices are now discovered by the driver.
- Reorganized _init() functions in start_kernel().
- Disk drives now show the ATA major version number.
- Reorganized the steps to do on a page fault in kernel mode.
- The kernel parameter 'ramdisksize=' no longer controls the size of the initrd
  image. [#34]
- The build of the Minix filesystem depends on the new option CONFIG_FS_MINIX
  (disabled by default).
- Fixed a bug in syscalls/wait4.c introduced in 9cfe372 that created malfunction
  in control jobs.
- Fixed to call sleep_init(), buffer_init(), sched_init() and inode_init()
  before initializing devices.
- Fixed the offset value in elf_load_interpreter() and elf_load().
- Fixed in pci_add_device() to use pci_read_short() instead of pci_read_char()
  for Command and Status registers.
- Fixed in do_execve() to reuse tmp_name allocated in sys_execve().
- Fixed a number of common variable definitions that prevented from build Fiwix
  with the newest GCC cross-compiler. [#10]
- Fixed in fs/namei.c to return ENOENT for missing directory. [#12]
- Fixed a bug in ext2_bmap() that prevented large files from persist on an ext2
  filesystem. [#14]
- Fixed a bug in v2_minix_bmap() that prevented large files from persist on a
  minix v2 filesystem. [#14]
- Fixed do_page_fault() to handle better a faulty address outside the user
  address space in kernel mode.
- Fixed the I/O address size in the ISA serial driver.
- Fixed a missing iput() in ext2_followlink() when there are too many nested
  symbolic links.
- Fixed a missing iput() in minix_followlink() when there are too many nested
  symbolic links.
- Fixed the hexadecimal values of /dev/tty10, /dev/tty11 and /dev/tty12 in
  kparms.h.
- Fixed some possible race conditions in buffer cache.
- Fixed a bug in mmap that prevented overlapped VMA regions from merging
  correctly. [#16]
- Fixed to terminate properly a read or write request on hdd timeout.
- Fixed a race condition in sys_nanosleep() when setting the processs sleeping
  time.
- Fixed merge_vma_regions() to free memory pages in overlapped segments. [#16]
- Fixed memory mapped files not written to disk correctly. [#18]
- Fixed sys_execve() to make sure arguments and environment do not exceed the
  maximum length. [#20]
- Fixed sys_mount() to use malloc_name() and free_name() to validate the
  argument 'fstype'.
- Fixed do_page_fault() to handle a page fault when trying to access a
  non-existent user stack address in kernel mode when
  CONFIG_LAZY_USER_ADDR_CHECK is enabled. [#22]
- Fixed verify_address() to accept a possible non-existent user stack address
  when CONFIG_LAZY_USER_ADDR_CHECK is disabled, since do_page_fault() will do
  the rest of the job. [#22]
- Fixed the logic in parse_arg() to support kernel parameters without arguments.
- Fixed a long standing bug where after removing an inode there was not a call
  to invalidate all its pages from the cache. [#24]
- Fixed a missing initialization in the PCI structure during scan_bus(). [#25]
- Fixed bread() to check if the bytes read matches with what was requested.
- Fixed premature output of information from the serial driver when acting as
  the remote console.
- Fixed frame buffer memory spaces to be marked as reserved if they conflict
  with available memory.
- Fixed sys_select() to return in the timeout argument the amount of time not
  slept. This is Linux specific but POSIX permits this behavior.
- Fixed Magic SysRq key 't' to also list zombie processes.
- Fixed Magic SysRq keys to work even when the tty has not been opened yet.
- Fixed get_free_page() to reduce the excessive number of iterations with
  reclaim_buffers() when running out of memory pages.
- Fixed the mechanism to sleep all processes in stop_kernel().
- Fixed the sleep address in page_lock() to match with page_unlock().
- Fixed a kernel panic if irq_keyboard() receives an unrecognized function key.
- Fixed to correctly disable the RAMdisk device if there is not enough physical
  memory.
- Fixed an inode-related race condition in iget() and iput().
- Fixed to not use the buffer after failed to be synced in sync_one_buffer().
- Fixed in ext2_symlink(), ext2_mkdir(), ext2_mknod() and ext2_create() to make
  sure the inode doesn't exist.
- Fixed in minix_symlink(), minix_mkdir(), minix_mknod() and minix_create() to
  make sure the inode doesn't exist.
- Fixed a deadlock between getblk() and kbdflushd(). [#27]
- Fixed a missing lock that led to a possible memory page corruption bug in
  bread_page(). [#27]
- Fixed atapi_cd_init() to setup the correct block size in the device structure.
- Fixed sys_ftruncate() to return EINVAL if its method does not exist.
- Fixed sync_superblocks() to sync all superblocks if argument is zero.
- Fixed the size on every symlink in procfs to 64 bytes.
- Fixed iget() to avoid locking when read_inode() returns an error.
- Fixed a missing call to sync_buffers() in close() methods of RAMdisk drive and
  floppy drive.
- Fixed serial_set_termios() to avoid a division by zero.
- Fixed script_load() with || instead of && that led to incorrectly recognize as
  script when there is an incomplete shebang.
- Fixed a linked list corruption when messages are retrieved not sequentially in
  sys_msgrcv().
- Fixed ata_hd_init() to not fail build if CONFIG_PCI is #undef.
- Fixed padding in fbcon_insert_char() to use character 0x20 instead of 0x00.
- Fixed vgacon_scroll_screen() to use double-buffering.
- Small fixes and cosmetic changes.


1.4.0 - 15-Nov-2022
===================
- Added support for the PCI local bus.
- Added support for the UNIX System V IPC mechanisms (semaphores, message queues
  and shared memory).
- Added the character device /dev/full.
- Added the character device /dev/port.
- Added the system call sys_getcwd. [#4]
- Added the configuration option CONFIG_QEMU_DEBUGCON to include support for the
  QEMU Bochs-style debug console.
- Improved the serial driver to support QEMU PCI serial devices.
- Removed the extra lock when dispatching the bottom halves.
- Mask the interrupt during the execution of the interrupt handler.
- Reorganized the code to separate interrupt related functions from specific pic
  functions.
- Moved set_leds() into the bottom half of the keyboard interrupt.
- Moved the start and stop tty functions into the bottom half of the keyboard
  interrupt.
- Removed the command to detect the interface type of the keyboard.
- Removed the kernel parameter 'noramdisk', so from now on the RAM disk driver
  is disabled by default. Use the kernel parameter 'ramdisksize=' to configure
  and enable it.
- Reversed the check order of schedule and signals before leaving the kernel
  space.
- Improved the cooperation with reclaim_buffers() when kernel runs out of memory
  pages.
- Added the functions inport_l() and outport_l() in core386.S.
- Added the sleeping address value in the SysRq process listing.
- Added the configuration option CONFIG_SYSCALL_6TH_ARG (disabled by default),
  to enable the 6th argument in the system calls.
- Added the configuration option CONFIG_LAZY_USER_ADDR_CHECK to relax the number
  of checks in the linear address of a system call parameter.
- Reorganized the signal functions to avoid that signals sent by the kernel have
  to use the same checking mechanism as if they were sent by a user process.
  This also fixes a permission problem when sending the SIGCHLD signal to a
  parent process owned by a different user, during the context of sys_exit().
- IDE driver now shows the PIO mode instead of UDMA mode, since the later is not
  supported yet.
- IDE driver now will use the current logical values if they are valid in the
  identify field.
- Changed the bios memory map functions to show that the ending address is
  inside each range.
- Changed sys_execve() to use the first argument instead of argv[0].
- Reverted 75bb49d and 4ecf9dd, as the PC emulator 'copy.sh/v86' (maybe others)
  requires to select the drive on every command.
- Fixed the slowness during the system boot-up caused by the keyboard driver not
  using interrupts during its own initialization.
- Fixed ext2_truncate() to return the error code after calling free_dblock().
- Fixed v1_minix_truncate() and v2_minix_truncate() to return the error code
  after calling free_zone().
- Fixed ext2_truncate() to correctly free doubly-indirect blocks.
- Fixed v1_minix_truncate() and v2_minix_truncate() to correctly free
  doubly-indirect blocks.
- Fixed ext2_truncate() to free triply-indirect blocks.
- Fixed v2_minix_truncate() to free triply-indirect blocks.
- Fixed the way how the I/O permission bitmap in TSS is implemented.
- Fixed the implementation of the sys_ioperm() system call.
- Fixed the execution permission logic that let root user execute any file.
- Fixed to handle SysRq key inside keyboard interrupt instead of in its bottom
  half.
- Fixed a missing inode release in elf_load() when argument list exceeds ARG_MAX
  on an ELF binary that requires an interpreter.
- Fixed a possible NULL pointer dereference with elf32_ph in elf_load() and
  elf_load_interpreter().
- Fixed the type of the user file descriptor (to unsigned int) in a number of
  system calls.
- Fixed a possible index out of bounds in bios_map_add().
- Fixed a missing validation in the arguments of sys_execve().
- Fixed an inefficiency in the mechanism of ext2_dir_readdir() and
  minix_dir_readdir().
- Fixed the function get_last_boot_addr() to return a proper address even when
  there are no ELF header tables. This mostly happens when the kernel is loaded
  using the QEMU argument '-kernel'.
- Fixed a possible out of bounds access in CHECK_UFD() macro.
- Fixed a possible out of bounds in utsname structures.
- Fixed UTS_MACHINE to return always 'i386' in all processor types on the i386
  architecture.
- Fixed do_printk() to show correctly the value of the second identifier when
  there are two consecutive identifiers
- Fixed to show the size of an ATA drive in KB if it's less than 1MB.
- Fixed to use the standard algorithm to convert LBA to CHS in the ATA driver.
- Fixed the TCSETSW, TCSETSF, TCSETAW and TCSETAF ioctl functions, so now they
  wait output buffer to drain before apply the new settings.
- Fixed a missing update of the termios structure during the ioctl functions:
  TCSETA, TCSETAW and TCSETAF
- Fixed sys_open() to check directory permissions only if the file does not
  exist and O_CREAT has been specified.
- Fixed callouts bottom half to avoid nesting.
- Fixed a bug introduced in 8eaed51 that prevented initrd images from
  working. [#7]
- Small fixes and cosmetic changes.
- Cleaned up a lot of code.


1.3.0 - 08-Dec-2021
===================
- Added support for interrupt nesting.
- Added framebuffer device support for VESA VBE 2.0+ compliant graphics cards.
- Added support for the framebuffer console (fbcon).
- Completely rewrite the console to support VGA text and framebuffer screens.
- Improved the speed of VGA text consoles by using double-buffering and fixing
  also a fair number of bugs.
- Updated the header file to support the latest GRUB Multiboot Specification v1.
- Moved 'cpu_idle()' to a C function to include more easily some tasks to do.
- Isolated the multiboot code in order to prepare the kernel to support multiple
  bootloader protocols.
- Arrange boot.S to be compatible only with GRUB Multiboot Specification v1.
- Changed from 0x90000 to 0x50000 the memory location of the 4MB temporary Page
  Directory to be able to hold bigger initrd images.
- Changed from 5% to 1% the amount of memory that will use the inode table.
- Added the ability to insert extra regions to the memory map provided by the
  boot loader.
- Added support to detect non-contiguous areas of available memory in the BIOS
  memory map.
- Added support for the 'magic SysRq key' to help to know the cause of a kernel
  freeze on a disaster situation.
- Added some basic checks on data received during IDE identify to make sure it
  makes sense.
- Added support to handle two ATA/ATAPI devices in the same IDE controller.
- Reduced the size of the buffer area used in floppy I/O operations.
- Increased to 50 the maximum of BIOS memory map entries.
- Removed CLI() functions in ide_hd and ide_cd.
- Improved the handling of the inode free list and the locking mechanism.
- Improved the handling of buffer and memory page free lists.
- Improved the way how is counted the first megabyte of memory.
- Changed bread_page() to reuse buffers and reduce disk I/O activity.
- Honour POSIX.1-2008 by returning ELOOP if flag O_NOFOLLOW is set and the
  trailing component (basename) of the pathname in open() is a symbolic link.
- Disabled interrupts during the context switch.
- Moved the values buffer->valid, buffer->locked and buffer->dirty to flags.
- Moved the value pg->locked to a flag.
- Changed kernel_process() to accept also the name of the process.
- Removed a sizeof(void) in sys_signal() as it is not covered by the C standard.
- Disabled interrupts during early boot up.
- Added the configure option CONFIG_VERBOSE_SEGFAULTS (disabled by default).
- Added a separate queue for all running processes.
- Disabled default screen blanking.
- Added a new linked list in the buffer structure to better handle the dirty
  buffers.
- Added the 'Dirty' line in '/proc/meminfo' to keep track the amount of memory
  waiting to be written back to the disk.
- Wakeup the INIT process (if it's sleeping on sys_wait4()) if one of the new
  processes inherited during the sys_exit() call is a zombie.
- Saved some CPU cycles in irq_handler() by isolating unused IRQs.
- Fixed the RAMdisk driver to not access blocks beyond its size.
- Fixed a race condition in floppy drive when the interrupt occurred right
  before going to sleep.
- Fixed a bug during the RAMdisk memory initialization that reserved twice the
  size of the initrd image.
- Fixed to return EISDIR when trying to read a directory in procfs.
- Fixed a memory corruption bug in procfs_readlink() that was leading to
  instability in user programs that read the procfs.
- Fixed to use a simple assignment in elf_create_stack() instead of using a
  function to copy a numeric value.
- Fixed a long standing memory corruption bug when returning the contents of the
  '/proc/<PID>/cmdline' file.
- Fixed a possible memory corruption bug when returning the contents of the
  '/proc/<PID>/environ' file.
- Fixed a missing queue handling in the serial driver.
- Fixed to remove the calls to reset termios and tty on tty_close().
- Fixed an extra buffer_head assignment in get_free_buffer() which reduced to
  50% the buffer space, and could also potentially use an already locked buffer.
- Fixed a very long standing buffer corruption bug, in rename functions of ext2
  and minix filesystems, that led to crashes with the message 'getblk(): no more
  buffers on free list!' after a heavy filesystem use.
- Fixed the tty_queue_room() function and aligned to 8 the number of cblocks per
  queue.
- Fixed the way how release_page() and reclaim_buffers() cooperate when there
  are no more free memory pages, in order to avoid killing the current process
  prematurely.
- Fixed to avoid sleeping during console_flush_log_buf().
- Fixed to return ENOSPC when trying to write beyond the size of a block device.
- Fixed get_proc_by_pid() to not PANIC anymore if the process didn't exist.
- Fixed to avoid multiple calls to tty_queue_init().
- Fixed to return ENXIO when the device does not exist.
- Fixed the CSI J Erase in Display (ED) and other sequences in console.
- Fixed /dev/kmem to not access beyond the end of the virtual memory.
- Fixed to make sure that disk partitions with status value other than 0x00 and
  0x80 are invalid.
- Fixed a race condition in ATA identify/read when the interrupt occurred right
  before going to sleep.
- Fixed a buffer overrun in iso9660_dir_readdir().
- Fixed a bug in iso9660_dir_readdir() that prevented from including some files
  in the user dirent structure under certain conditions.
- Fixed a very long standing bug in the memory page hashing mechanism that led
  to kernel freezes after a long use.
- Fixed a very long standing bug in all inode lookup functions that ate an extra
  inode on every call, leading to the premature message "WARNING: no more inodes
  on free list!".
- Fixed certain values to be signed instead of unsigned in kstat structure.
- Fixed a bug in tty->canon_data that corrects a bad behavior in select().
- Fixed to decrease rss memory from the zombie process instead from its parent
  in remove_zombie().
- Fixed to name correctly the IDLE process by assigning 'idle' to argv0.
- Fixed to honour the select() function when handling pipes.
- Fixed to reduce over-scheduling in tty_write() by calling do_sched() only if
  needed.
- Fixed a long standing bug in do_exit() that made some processes returning from
  the death.
- Fixed the inode reference counter when moving directories (sys_rename) in ext2
  and minix filesystems.
- Fixed to update the parent directory when moving directories (sys_rename) in
  ext2 and minix filesystems.
- Fixed to wake up all processes in select() after a console_write().
- Fixed an incomplete copy of in-memory superblock data during a remount from RO
  to RW, in ext2 and minix filesystems, that led to not save all changes in
  superblock.
- Fixed to decrease the number of children either when the process is exiting,
  and from the correct parent after reaping a zombie process.
- Fixed a long standing bug, in ext2_dir_readdir() and minix_dir_readdir(), that
  prevented from listening directory entries if there were blank blocks in the
  middle.
- Small fixes and cosmetic changes.
- Cleaned up a lot of code.


1.2.0 - 12-Dec-2020
===================
- Added support for serial (RS-232) devices.
- Completely rewritten the way how the device table is handled.
- Completely rewritten the way how the interrupt table is handled.
- Added the ability to share the same IRQ between multiple devices.
- Completely rewritten the way how bottom halves are managed.
- Added the 'doc/devices.txt' document.
- Added basic functionality of OPOST functions to tty.
- Added to reschedule the keyboard bottom-half if it was busy.
- Added support of O_NONBLOCK in tty_write().
- Added remote serial console support.
- Added support for K_RAW and K_MEDIUMRAW keyboard modes.
- Added and fixed some ECMA-48 CSI sequences in console.
- Improved termios and other aspects of the tty driver to accomodate the new
  serial driver.
- Small optimizations and bug fixes in console.
- Improved the macros that build the interrupt service routines.
- Fixed to force some signals that a process cannot ignore by changing their
  dispositions to SIG_DFL.
- Fixed a bug in tty_read and tty_write that caused to send the SIGTTIN signal
  to the foreground process.
- Fixed nanosleep() to force to 10ms any request lower than 10ms.
- Fixed a signedness bug in setreuid() and setregid().
- Fixed to delimitate better the stack-related page faults in the vma region.
- Fixed a NULL pointer dereference when __DEBUG__ is enabled in sys_waitpid().
- Fixed to avoid freeing an invalid page that generated PANICs in SVGAlib
  programs.
- Fixed a bug that, under certain conditions, page_not_present() unmapped a
  wrong page number.
- Fixed to not clone MAP_SHARED pages during fork().
- Saved twice the 'signum' value before calling the signal handler.
- Small fixes and cosmetic changes.


1.1.0 - 24-Mar-2020
===================
- Added support for an initial RAMdisk (initrd) image.
- Added full support for the ext2 filesystem.
- Added support to execute scripts.
- Limit the number of messages on spurious interrupts.
- RAMdisks initialization now shows the range of the memory addresses of each
  RAMdisk created.
- Added VMA_REGIONS as a general configurable option (default: 150 entries).
- Changed the default kernel filesystem to ext2.
- Renamed the sleep addresses in tty.c.
- Added the ability to pass arguments to init from the kernel's command line.
- Included memory values in /proc/PID/stat and /proc/PID/status.
- Included the file /proc/PID/statm to provide more information about memory
  usage.
- Changed the ATA's SET MULTIPLE MODE command to do all I/O with 4KB block size
  (8 sectors) by default.
- Fixed to prevent from using an unexistent floppy type, in the fdd_type
  structure, if CMOS returns a value bigger than 0x04.
- Fixed a misplaced bitwise operator AND that was not ensuring the limitation
  to 1GB as the amount of physical memory supported.
- Fixed some bugs in *_minix_ialloc() and minix_balloc() when they fail.
- Fixed a malfunction in the job control.
- Fixed in sys_getgroups() to return the number of group IDs when the argument
  size is zero.
- Fixed the DEC Set Top and Bottom Margins (DECSTBM) sequence, which affected
  the scroll up mechanism in consoles.
- Fixed to set properly the timestamp on every read and write in all ttys.
- Fixed the start time value in /proc/PID/stat of every single process.
- Fixed to use a long long variable type to be able support block devices bigger
  than 4GB.
- Fixed a memory corruption bug processing the VT100 'CSI n J' sequence.
- Small fixes and cosmetic changes.


1.0.1 - 04-Aug-2018
===================
- Added a basic implementation of a Pseudo-Random Number Generator using the
  character devices /dev/random and /dev/urandom.
- Improved the mechanism in procfs_dir_readdir() to fix a memory corruption bug.
- Fixed a bug in procfs_dir_readdir() that prevented from reading correctly the
  entire procfs root directory.
- Fixed a bug in iso9660_dir_readdir() that prevented from reading correctly any
  directory.
- Fixed to show the complete pathname in the argv[0] of the init process.
- Fixed to protect INIT process from unexpected signals.


1.0.0 - 23-Apr-2018
===================
- Fixed a bug in reclaim_buffers() to avoid kernel freeze.
- Fixed a corruption bug when creating the dirent structure in the dir_readdir()
  functions.
- Massive code cleaning.
- New system calls:
	sys_select