[metal] Add a uprintf() routine, for non-emergency boot logging (#905)

* [metal] Add a uprintf() routine, for non-emergency boot logging
* [metal] _Really_ push forward timing of VGA TTY initialization
* [metal] Do something useful with uprintf()
* [metal] Locate some ACPI tables, for later hardware detection

Specifically the code now tries to find the ACPI RSDP,
RSDT/XSDT, FADT, & MADT tables, whether in legacy BIOS
bootup mode or in a UEFI bootup.  These are useful for
figuring out how to (re)enable asynchronous interrupts
in legacy 8259 PIC mode.

libc/intrin/interrupts.S

@@ -25,7 +25,9 @@
 │ OTHER DEALINGS IN THE SOFTWARE.                                              │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/dce.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/macros.internal.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/runtime/pc.internal.h"
 
 //	Code and data structures for bare metal interrupt handling.

libc/intrin/kprintf.greg.c

@@ -385,14 +385,29 @@ privileged long kloghandle(void) {
   return __klog_handle;
 }
 
+privileged void _klog_serial(const char *b, size_t n) {
+  size_t i;
+  uint16_t dx;
+  unsigned char al;
+  for (i = 0; i < n; ++i) {
+    for (;;) {
+      dx = 0x3F8 + UART_LSR;
+      asm("inb\t%1,%0" : "=a"(al) : "dN"(dx));
+      if (al & UART_TTYTXR) break;
+      asm("pause");
+    }
+    dx = 0x3F8;
+    asm volatile("outb\t%0,%1"
+                 : /* no inputs */
+                 : "a"(b[i]), "dN"(dx));
+  }
+}
+
 privileged void klog(const char *b, size_t n) {
 #ifdef __x86_64__
   int e;
   long h;
-  size_t i;
-  uint16_t dx;
   uint32_t wrote;
-  unsigned char al;
   long rax, rdi, rsi, rdx;
   if ((h = kloghandle()) == -1) {
     return;
@@ -407,18 +422,7 @@ privileged void klog(const char *b, size_t n) {
     if (_weaken(_klog_vga)) {
       _weaken(_klog_vga)(b, n);
     }
-    for (i = 0; i < n; ++i) {
-      for (;;) {
-        dx = 0x3F8 + UART_LSR;
-        asm("inb\t%1,%0" : "=a"(al) : "dN"(dx));
-        if (al & UART_TTYTXR) break;
-        asm("pause");
-      }
-      dx = 0x3F8;
-      asm volatile("outb\t%0,%1"
-                   : /* no inputs */
-                   : "a"(b[i]), "dN"(dx));
-    }
+    _klog_serial(b, n);
   } else {
     asm volatile("syscall"
                  : "=a"(rax), "=D"(rdi), "=S"(rsi), "=d"(rdx)
@@ -1152,3 +1156,6 @@ privileged void kprintf(const char *fmt, ...) {
   kvprintf(fmt, v);
   va_end(v);
 }
+
+__weak_reference(kprintf, uprintf);
+__weak_reference(kvprintf, uvprintf);

libc/intrin/kprintf.h

@@ -9,25 +9,49 @@
 #define kvsnprintf   __kvsnprintf
 #define kloghandle   __kloghandle
 #define kisdangerous __kisdangerous
+#define uprintf      __uprintf
+#define uvprintf     __uvprintf
 
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
+
 COSMOPOLITAN_C_START_
 
-void kprintf(const char *, ...);
-size_t ksnprintf(char *, size_t, const char *, ...);
-void kvprintf(const char *, va_list);
-size_t kvsnprintf(char *, size_t, const char *, va_list);
-bool kisdangerous(const void *);
-
 void kprintf(const char *, ...);
 size_t ksnprintf(char *, size_t, const char *, ...);
 void kvprintf(const char *, va_list);
 size_t kvsnprintf(char *, size_t, const char *, va_list);
 
 bool kisdangerous(const void *);
+
 void klog(const char *, size_t);
+void _klog_serial(const char *, size_t);
 long kloghandle(void);
 
+void uprintf(const char *, ...);
+void uvprintf(const char *, va_list);
+
+#ifndef TINY
+#define KINFOF(FMT, ...)                                      \
+        do {                                                  \
+          uprintf("\r\e[35m%s:%d: " FMT "\e[0m\n",            \
+                  __FILE__, __LINE__, ## __VA_ARGS__);        \
+        } while (0)
+#define KWARNF(FMT, ...)                                      \
+        do {                                                  \
+          uprintf("\r\e[94;49mwarn: %s:%d: " FMT "\e[0m\n",   \
+                  __FILE__, __LINE__, ## __VA_ARGS__);        \
+        } while (0)
+#else
+#define KINFOF(FMT, ...) ((void)0)
+#define KWARNF(FMT, ...) ((void)0)
+#endif
+#define KDIEF(FMT, ...)                                       \
+        do {                                                  \
+          kprintf("\r\e[30;101mfatal: %s:%d: " FMT "\e[0m\n", \
+                  __FILE__, __LINE__, ## __VA_ARGS__);        \
+          for (;;) asm volatile("cli\n\thlt");                \
+        } while (0)
+
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
 #endif /* _COSMO_SOURCE */