Simplify AT_SEL4_BOOT_INFO environment handling.

The runtime environment setup was setting bootinfo, ipc_buffer, and
the thread tcb when processing AT_SEL4_BOOT_INFO. Instead set only the
bootinfo reference and require the caller pass AT_SEL4_IPC_BUFFER and
AT_SEL4_TCB to setup the other data.

Change-Id: I06e01ff7e600318bc428f7506c38413aa1893019

src/env.c

diff --git a/src/env.c b/src/env.c
index ed627f8..f00bf61 100644
--- a/src/env.c
+++ b/src/env.c
@@ -302,13 +302,7 @@
             break;
         }
         case AT_SEL4_BOOT_INFO: {
-            seL4_BootInfo *bootinfo = auxv[i].a_un.a_ptr;
-            if (bootinfo == SEL4RUNTIME_NULL) {
-                break;
-            }
-            env.bootinfo = bootinfo;
-            env.initial_thread_ipc_buffer = bootinfo->ipcBuffer;
-            env.initial_thread_tcb = seL4_CapInitThreadTCB;
+            env.bootinfo = auxv[i].a_un.a_ptr;
             break;
         }
         case AT_SEL4_IPC_BUFFER_PTR: {

src/start_root.c

diff --git a/src/start_root.c b/src/start_root.c
index fe6aa39..374d7f5 100644
--- a/src/start_root.c
+++ b/src/start_root.c
@@ -58,7 +58,7 @@
     struct {
         char const *const argv[2];
         char const *const envp[2];
-        auxv_t auxv[7];
+        auxv_t auxv[8];
     } info = {
         .argv = {
             "rootserver",
@@ -85,6 +85,9 @@
                 .a_type = AT_SEL4_BOOT_INFO,
                 .a_un.a_ptr = boot_info,
             }, {
+                .a_type = AT_SEL4_IPC_BUFFER_PTR,
+                .a_un.a_ptr = boot_info->ipcBuffer,
+            }, {
                 .a_type = AT_SEL4_TCB,
                 .a_un.a_val = seL4_CapInitThreadTCB,
             }, {