first usable version of kernel and commands

After an year of hard work, this is a first "usable" version of Jehanne.

qa/kern/pipering.c

@@ -0,0 +1,70 @@
+#include <u.h>
+#include <libc.h>
+
+int nring = 32;
+int niter = 1024;
+int debug = 0;
+char data[8192];
+int i;
+int id;
+int intr = 0;
+
+void
+handler(void *v, char *s)
+{
+	print("%d: %d iterations\n", id, i);
+	if (intr++ < 16)
+		noted(NCONT);
+	exits("too many interrupts");
+}
+
+void
+main(int argc, char *argv[])
+{
+	int pid;
+
+	if (notify(handler)){
+		sysfatal("notify: %r");
+	}
+
+	if (argc > 1)
+		nring = strtoull(argv[1], 0, 0);
+
+	if (argc > 2)
+		niter = strtoull(argv[2], 0, 0);
+	debug = argc > 3;
+
+	fprint(2, "Running with %d pipes %d times\n", nring, niter);
+	int *pfd = malloc(sizeof(int)* nring * 2);
+
+	if (pfd == nil)
+		sysfatal(smprint("alloc %d pipes: %r", nring*2));
+
+	for(i = 0; i < nring; i++)
+		if (pipe(&pfd[i*2]) < 0)
+			sysfatal(smprint("create pipe pair %d of %d: %r", i, nring));
+
+	for(i = 0; debug && i < nring; i++ ) fprint(2, "pfd[%d,%d]\n", pfd[i*2],pfd[i*2+1]);
+	for(i = 0, id = 0; i < nring-1; i++, id++) {
+		pid = fork();
+		if (pid == 0)
+			break;
+		if (pid < 0)
+			sysfatal("fork");
+	}
+
+	if (debug) fprint(2, "Forked. pid %d\n", getpid());
+	for(i = 0; debug && i < nring; i++ ) fprint(2, "pfd[%d,%d]\n", pfd[i*2],pfd[i*2+1]);
+	for(i = 0; i < niter; i++) {
+		if (debug) fprint(2, "%d: write %d\n", id, pfd[(id%nring)*2+1]);
+		int amt = write(pfd[(id%nring)*2+1], data, sizeof(data));
+		if (amt < sizeof(data))
+			sysfatal(smprint("%d: write only got %d of %d: %r", id, amt, sizeof(data)));
+		if (debug) print("%d: read %d\n", id, pfd[(id%nring)*2]);
+		amt = read(pfd[(id%nring)*2], data, sizeof(data));
+		if (amt < sizeof(data))
+			sysfatal(smprint("%d: read only got %d of %d: %r", id, amt, sizeof(data)));
+	}
+	print("PASS\n");
+	exits("PASS");
+}