[Minios-devel] [UNIKRAFT PATCH 1/5] lib/ukboot: Application constructors right before calling application

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

preinit and init tables are part of ported libraries and applications.
Since they are originally run in user space on Linux or BSD, they
expect fully initialized kernel layers. The constructor functions
listed in those tables could create threads, allocate memory, or
interact with the VFS, etc.
This patch moves calling those constructors at the latest possible point.

Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
---
 lib/ukboot/boot.c | 52 +++++++++++++++++++++++++++--------------------
 1 file changed, 30 insertions(+), 22 deletions(-)

diff --git a/lib/ukboot/boot.c b/lib/ukboot/boot.c
index 9738a912..b4b390ef 100644
--- a/lib/ukboot/boot.c
+++ b/lib/ukboot/boot.c
@@ -83,28 +83,6 @@ static void main_thread_func(void *arg)
        int ret;
        struct thread_main_arg *tma = arg;
 
-       uk_pr_info("Pre-init table at %p - %p\n",
-                  __preinit_array_start, &__preinit_array_end);
-       ukplat_ctor_foreach(__preinit_array_start, __preinit_array_end, i) {
-               if (__preinit_array_start[i]) {
-                       uk_pr_debug("Call pre-init constructor (entry %d (%p): 
%p())...\n",
-                                   i, &__preinit_array_start[i],
-                                   __preinit_array_start[i]);
-                       __preinit_array_start[i]();
-               }
-       }
-
-       uk_pr_info("Constructor table at %p - %p\n",
-                       __init_array_start, &__init_array_end);
-       ukplat_ctor_foreach(__init_array_start, __init_array_end, i) {
-               if (__init_array_start[i]) {
-                       uk_pr_debug("Call constructor (entry %d (%p): 
%p())...\n",
-                                       i, &__init_array_start[i],
-                                       __init_array_start[i]);
-                       __init_array_start[i]();
-               }
-       }
-
 #ifdef CONFIG_LIBUKBUS
        uk_pr_info("Initialize bus handlers...\n");
        uk_bus_init_all(uk_alloc_get_default());
@@ -130,6 +108,36 @@ static void main_thread_func(void *arg)
        printf("%35s\n",
               STRINGIFY(UK_CODENAME) " " STRINGIFY(UK_FULLVERSION));
 #endif
+       /*
+        * Application
+        *
+        * We are calling the application constructors right before calling
+        * the application's main(). All of our Unikraft systems, VFS,
+        * networking stack is initialized at this point. This way we closely
+        * mimic what a regular user application (e.g., BSD, Linux) would expect
+        * from its OS being initialized.
+        */
+       uk_pr_info("Pre-init table at %p - %p\n",
+                  __preinit_array_start, &__preinit_array_end);
+       ukplat_ctor_foreach(__preinit_array_start, __preinit_array_end, i) {
+               if (__preinit_array_start[i]) {
+                       uk_pr_debug("Call pre-init constructor (entry %d (%p): 
%p())...\n",
+                                   i, &__preinit_array_start[i],
+                                   __preinit_array_start[i]);
+                       __preinit_array_start[i]();
+               }
+       }
+
+       uk_pr_info("Constructor table at %p - %p\n",
+                       __init_array_start, &__init_array_end);
+       ukplat_ctor_foreach(__init_array_start, __init_array_end, i) {
+               if (__init_array_start[i]) {
+                       uk_pr_debug("Call constructor (entry %d (%p): 
%p())...\n",
+                                       i, &__init_array_start[i],
+                                       __init_array_start[i]);
+                       __init_array_start[i]();
+               }
+       }
 
        uk_pr_info("Calling main(%d, [", tma->argc);
        for (i = 0; i < tma->argc; ++i) {
-- 
2.20.1


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