illumos gate

Quicky hack I used for narrowing down that memory region:

diff --git a/usr/src/cmd/bhyve/bhyverun.c b/usr/src/cmd/bhyve/bhyverun.c
index c777529858..841cf2ed70 100644
--- a/usr/src/cmd/bhyve/bhyverun.c
+++ b/usr/src/cmd/bhyve/bhyverun.c
@@ -1365,6 +1365,39 @@ set_defaults(void)
        set_config_bool("x86.strictmsr", true);
 }

+static void
+prezero_mem(struct vmctx *ctx, const char *opt)
+{
+       char *buf, *save;
+       const char *start, *len;
+       unsigned long nstart = ULONG_MAX, nlen = ULONG_MAX;
+
+
+       buf = strdup(opt);
+       start = strtok_r(buf, ":", &save);
+       len = strtok_r(NULL, ":", &save);
+
+       if (len != NULL) {
+               nstart = strtoul(start, NULL, 16);
+               nlen = strtoul(len, NULL, 16);
+       }
+       if (nstart == ULONG_MAX || nlen == ULONG_MAX) {
+               fprintf(stderr, "Could not parse memory pre-zero range: '%s'\n",
+                  opt);
+               exit(1);
+       }
+
+       void *zero_region = vm_map_gpa(ctx, nstart, nlen);
+       if (zero_region == NULL) {
+               fprintf(stderr, "Invalid pre-zeroing region: [%lx, %lx)\n",
+                   nstart, nstart + nlen );
+               exit(1);
+       }
+
+       bzero(zero_region, nlen);
+       fprintf(stderr, "Pre-zeroed [%lx, %lx)\n", nstart, nstart + nlen);
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -1572,6 +1605,13 @@ main(int argc, char *argv[])
                exit(4);
        }

+#ifndef        __FreeBSD__
+       value = get_config_value("memory.prezero");
+       if (value != NULL) {
+               prezero_mem(ctx, value);
+       }
+#endif
+
        error = init_msr();
        if (error) {
                fprintf(stderr, "init_msr error %d", error);