Rename Schunix to SchOS; the kernel becomes SchIFT

Removes the "-unix" element and with it any trademark exposure to The
Open Group.

The split follows the ecosystem layout: SchOS is the system, and the
kernel has its own name. Kernel-identity strings are the only places
that take SchIFT -- uname(2) sysname, /proc/version, and the two licence
sentences that say "kernel" outright. That is what every Unix does here:
`uname -s` on Linux reports the kernel, not the distribution. Everything
a user reads as the product -- panic screen, boot menu, error prefixes,
docs, LICENSE, NOTICE -- is SchOS.

schunix.img is schos.img, the logo assets and the musl TLS patch are
renamed, and __SCHUNIX__ is __SCHOS__ (the define and the patch that
consumes it moved together).

Two things the rename broke, both found by the bootcheck suite:

  - shmtest wrote "SCHUNIX-MMAP-OK" with a hardcoded length of 15 and
    compared it back by hand-counted offsets (m[3]=='U', m[14]=='K').
    The shorter marker left the write running two bytes past the literal
    and the compare reading past the data, failing a file-backed mmap
    that was working correctly. Now written and compared through one
    constant with sizeof.
  - bootcheck asserted a 31-byte file after appending to
    "hello-from-schunix"; the shorter string makes it 29.

Both are the same mistake: a string literal whose length is written out
somewhere else. Full suite green -- base, Tty, Ps, Sock, Fb, Usb, Evdev.

kernel/arch/x86_64/e820.c

@@ -5,7 +5,7 @@
 // it is an assertion that exactly that much exists. Boot a machine with less
 // and kinit1() walks off the end of RAM into nothing; boot one with more and
 // every byte above 224 MB is invisible. Measured before this file existed:
-// Schunix booted at 224 MB and triple faulted at 192 MB, for no reason at all.
+// SchOS booted at 224 MB and triple faulted at 192 MB, for no reason at all.
 //
 // The firmware has known the answer the whole time. boot/stage2.S asks it with
 // INT 0x15 / E820 in real mode -- the same interface Linux's boot stub and GRUB
@@ -92,7 +92,7 @@ e820_init(void)
   // Below this the kernel image, its page tables and the DMA arena do not fit,
   // and continuing produces a failure much harder to read than this line.
   if (top < PHYSTOP_MIN) {
-    cprintf("e820: only %d MB usable; Schunix needs at least %d MB\n",
+    cprintf("e820: only %d MB usable; SchOS needs at least %d MB\n",
             (int)(top / (1024 * 1024)), (int)(PHYSTOP_MIN / (1024 * 1024)));
     // Left at the fallback deliberately rather than lowered: a machine this
     // small is going to fail, and it should fail having said why.

kernel/arch/x86_64/vm.c

@@ -142,7 +142,7 @@ seginit(void)
   //                and SS from +8, so the *slot* must exist to keep the
   //                [UCODE32, UDATA, UCODE] triple consecutive. See syscallinit.
   //   SEG_KCPU     is a leftover slot number from 32-bit xv6, where %gs held the
-  //                per-CPU pointer. Schunix uses FS_BASE/TLS instead, but the
+  //                per-CPU pointer. SchOS uses FS_BASE/TLS instead, but the
   //                index has to stay occupied or SEG_TSS stops landing at 7.
   //
   // Deleting either moves every descriptor after it and breaks sysret.

kernel/core/main.c

@@ -13,7 +13,7 @@ static void mpmain(void)  __attribute__((noreturn));
 extern char end[]; // first address after kernel loaded from ELF file
 
 // Set by stage2main.c (boot/stage2main.c, BOOT_VERBOSE_FLAG_ADDR) when the
-// user picks "Boot Schunix (verbose)" from the F8 boot menu; read once here,
+// user picks "Boot SchOS (verbose)" from the F8 boot menu; read once here,
 // before anything else, so subsystem init can log its own steps.
 int boot_verbose;
 

kernel/core/panic.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Apache-2.0
 //
-// PSOGM — the Schunix crash screen.
+// PSOGM — the SchOS crash screen.
 //
 // The name is a nod to the Amiga's "Guru Meditation", but nothing else about
 // this is a nod to 1985. Three things it is built around:
@@ -439,7 +439,7 @@ paint(char *reason, addr_t *pcs, int npcs)
 
   // Left-aligned, not centred. Centred text reads as a poster; this is a
   // report, and a report is read down the left edge.
-  vga_text_at(left, y, "Schunix ran into a problem and needs to restart.",
+  vga_text_at(left, y, "SchOS ran into a problem and needs to restart.",
               PSOGM_FG);
   y += ch + ch / 2;
   vga_text_at(left, y, "Nothing on your disks was touched by this.",
@@ -492,7 +492,7 @@ report_serial(char *reason, addr_t *pcs, int npcs)
 {
   cprintf("\n");
   cprintf("  :(\n\n");
-  cprintf("  Schunix ran into a problem and needs to restart.\n");
+  cprintf("  SchOS ran into a problem and needs to restart.\n");
   cprintf("  PSOGM -- Purple Screen of Guru Meditation\n\n");
 
   for (int i = 0; i < nfields; i++) {

kernel/core/time.c

@@ -3,7 +3,7 @@
 // The kernel has always known how long it had been running -- `ticks`, bumped
 // 100 times a second by the timer interrupt -- and has never known what time it
 // was. sys_gettimeofday() returned `ticks / 100` as though it were seconds
-// since the epoch, so every Schunix machine believed it was the 1st of January
+// since the epoch, so every SchOS machine believed it was the 1st of January
 // 1970 and that the date advanced at the rate of its own uptime. `date` printed
 // a number that barely moved, which is what it looks like when a clock is
 // counting from the wrong place rather than not counting at all.

kernel/dev/device.c

@@ -281,7 +281,7 @@ text_selftest(void)
   int line = f->ops->height(f) + 6;
   int y = 80;
 
-  text_draw(&s, f, 60, y + base, "Schunix text rendering", SCH_FG);
+  text_draw(&s, f, 60, y + base, "SchOS text rendering", SCH_FG);
   y += line * 2;
 
   // Deliberately not on a multiple of eight. On the old console this string

kernel/dev/fb.c

@@ -179,7 +179,7 @@ fb_ioctl(int request, addr_t arg)
     if (!f)
       return -EFAULT;
     memset(f, 0, sizeof(*f));
-    safestrcpy(f->id, "schunixfb", sizeof(f->id));
+    safestrcpy(f->id, "schosfb", sizeof(f->id));
     f->smem_start  = (unsigned long)vga_fb_phys();
     f->smem_len    = (unsigned int)vga_fb_size();
     f->type        = FB_TYPE_PACKED_PIXELS;

kernel/dev/procfs.c

@@ -143,7 +143,7 @@ gen_cpuinfo(struct sbuf *sb)
   // otherwise be told a VM with four processors has four to schedule on, when
   // three of them are enumerated and idle. "cpu cores" stays the present count,
   // which is what that field means.
-  // Real values, from CPUID. These used to read "Schunix" and "Schunix virtual
+  // Real values, from CPUID. These used to read "SchOS" and "SchOS virtual
   // CPU" -- a thing to print when you have not asked the processor, and
   // actively unhelpful, because identifying the machine is the one question
   // /proc/cpuinfo exists to answer.
@@ -204,7 +204,8 @@ gen_cpuinfo(struct sbuf *sb)
 static void
 gen_version(struct sbuf *sb)
 {
-  sb_puts(sb, "Schunix version 0.1.0 (schunix) #1 SMP x86_64\n");
+  // The kernel's name, not the system's -- same as "Linux version 6.x" here.
+  sb_puts(sb, "SchIFT version 0.1.0 (schift) #1 SMP x86_64\n");
 }
 
 static void

kernel/dev/ttf.c

@@ -200,7 +200,7 @@ load_outline(struct ttf *f, int gid, struct outline *o)
   // A negative contour count means a composite: the glyph is other glyphs
   // placed at offsets. This is not an exotic case to skip -- `i` is built from
   // a dotless i plus the dot, so skipping composites loses a letter from
-  // "Schunix", which is exactly how the gap was found.
+  // "SchOS", which is exactly how the gap was found.
   //
   // Only the translated case is handled: components with a scale or a 2x2
   // matrix are rare outside of synthesised obliques, and applying a transform

kernel/dev/uart.c

@@ -41,7 +41,7 @@ uartearlyinit(void)
 
 
   // Announce that we're here.
-  for(p="Schunix UART...\n"; *p; p++)
+  for(p="SchOS UART...\n"; *p; p++)
     uartputc(*p);
 }
 

kernel/fs/exec.c

@@ -11,7 +11,7 @@
 #include "errno.h"
 
 // Binaries with entry points at 0x100000+ are musl/Linux-ABI.
-// Schunix-native binaries (init) are linked at 0x4000.
+// SchOS-native binaries (init) are linked at 0x4000.
 #define LINUX_ABI_ENTRY_THRESHOLD 0x100000UL
 extern int linux_syscall_map[];
 extern int linux_syscall_map_size;
@@ -158,7 +158,7 @@ exec(char *path, char **argv)
   }
 
   // Auto-select syscall ABI: musl binaries have entry >= 0x100000;
-  // Schunix-native binaries (init) are linked at 0x4000.
+  // SchOS-native binaries (init) are linked at 0x4000.
   if (elf.entry >= LINUX_ABI_ENTRY_THRESHOLD) {
     myproc()->syscall_map = linux_syscall_map;
     myproc()->map_size    = linux_syscall_map_size;

kernel/fs/file.c

@@ -152,7 +152,7 @@ fileread(struct file *f, char *addr, int n)
     }
 
     if((f->ip->rwmode & 2) == 0){
-      cprintf("Schunix: permission denied (read)\n");
+      cprintf("SchOS: permission denied (read)\n");
       iunlock(f->ip);
       return -1;
     }
@@ -208,7 +208,7 @@ filewrite(struct file *f, char *addr, int n)
     }
 
     if((f->ip->rwmode & 1) == 0){
-      cprintf("Schunix: permission denied (write)\n");
+      cprintf("SchOS: permission denied (write)\n");
       iunlock(f->ip);
       return -1;
     }

kernel/fs/procfs.c

@@ -133,7 +133,7 @@ static void sbputi(struct sb *s, int64 v)
 // Linux's /proc/<pid>/stat, as far as anything here reads it.
 //
 // The field order is not negotiable: ps counts fields by position, so a
-// missing one silently shifts everything after it. Fields Schunix does not
+// missing one silently shifts everything after it. Fields SchOS does not
 // track are zero, which is what Linux itself reports for things a given
 // process has never done.
 static char

kernel/fs/schfs/kmount.c

@@ -532,7 +532,7 @@ schfs_kroot(void)
 /* Phase 2 has no VFS integration -- SchFS files are not reachable      */
 /* through open(2) yet -- so this is how the mount is observable from   */
 /* userland at all. It reports the volume and lists the root directory, */
-/* which is enough to confirm from inside a running Schunix that the    */
+/* which is enough to confirm from inside a running SchOS that the    */
 /* kernel really did parse an image mkschfs wrote.                      */
 /* ------------------------------------------------------------------ */
 

kernel/sys/linux_abi.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: Apache-2.0
-// Linux x86_64 syscall number -> Schunix syscall number translation.
+// Linux x86_64 syscall number -> SchOS syscall number translation.
 // Enabled per process by sys_enable_linux_abi (see kernel/sys/sys_compat.c).
 //
 // This file used to be the second half of a two-place registration scheme: a
@@ -16,7 +16,7 @@
 
 #define LINUX_NSYSCALL NSYSCALLS
 
-// Index: Linux x86_64 syscall number. Value: Schunix SYS_* number, or 0 for
+// Index: Linux x86_64 syscall number. Value: SchOS SYS_* number, or 0 for
 // "not implemented" (syscall() then returns -ENOSYS).
 //
 // Syscalls declared NO_LINUX in table.inc all land on the single scratch index

kernel/sys/sys_compat.c

@@ -114,8 +114,8 @@ sys_uname(void)
     struct utsname *u = (struct utsname*)user_ptr(ubuf, sizeof(*u));
     if (!u) return -EFAULT;
     memset(u, 0, sizeof(*u));
-    memmove(u->sysname,    "Schunix",  8);
-    memmove(u->nodename,   "schunix",  8);
+    memmove(u->sysname,    "SchIFT",   7);
+    memmove(u->nodename,   "schos",    6);
     memmove(u->release,    "0.1.0",    6);
     memmove(u->version,    "#1",       3);
     memmove(u->machine,    "x86_64",   7);

kernel/sys/sys_fs.c

@@ -18,7 +18,7 @@
 // -----------------------------------------------------------------------
 // Linux-ABI-compatible struct stat (x86_64 "struct stat" from
 // musl 1.2.5 bits/stat.h) — musl/toybox/dash parse st_mode directly
-// out of this exact byte layout, which bears no resemblance to Schunix's
+// out of this exact byte layout, which bears no resemblance to SchOS's
 // own native `struct stat` (stat.h). Without this, every Linux-ABI process
 // reading stat() results (e.g. ls checking S_ISDIR to decide whether to
 // list a directory or just print its name) gets garbage.
@@ -825,7 +825,7 @@ sys_getdents64(void)
 }
 
 // -----------------------------------------------------------------------
-// Custom SchunixFS ops
+// Custom SchOSFS ops
 // -----------------------------------------------------------------------
 
 addr_t sys_delete(void)

kernel/sys/table.inc

@@ -1,7 +1,7 @@
 // Segregated Kernel -- central syscall table. ONE line per syscall.
 //
 // Format: SYSCALL(nr, linux_nr, name)
-//   nr        Schunix native syscall number
+//   nr        SchOS native syscall number
 //   linux_nr  Linux x86_64 syscall number, or NO_LINUX if none
 //   name      implemented as sys_<name>() in kernel/sys/sys_*.c
 //
@@ -120,7 +120,7 @@ SYSCALL( 60,         16, ioctl)
 // translation answered "bad syscall" before the stub could answer ENOSYS.
 // Now that they do something they need the numbers programs actually use.
 //
-// `shutdown` is deliberately not the name here: Schunix already has a native
+// `shutdown` is deliberately not the name here: SchOS already has a native
 // shutdown() that powers the machine off (syscall 32), and two syscalls
 // cannot share a sys_ function name. Linux 48 maps to sockshutdown instead.
 SYSCALL( 40,         41, socket)