Merge pull request #1462 from fwsGonzo/dev

solo5: Add support for pre-BSS memory hole, fix start issue

Author: alfreb

cmake/post.service.cmake

@@ -223,8 +223,13 @@ if (${ELF} STREQUAL "i686")
   set(ELF "i386")
 endif()
 
+set(PRE_BSS_SIZE  "--defsym PRE_BSS_AREA=0x0")
+if ("${PLATFORM}" STREQUAL "x86_solo5")
+  # pre-BSS memory hole for uKVM global variables
+  set(PRE_BSS_SIZE  "--defsym PRE_BSS_AREA=0x200000")
+endif()
 
-set(LDFLAGS "-nostdlib -melf_${ELF} -N --eh-frame-hdr ${STRIP_LV} --script=${INSTALL_LOC}/${ARCH}/linker.ld ${INSTALL_LOC}/${ARCH}/lib/crtbegin.o")
+set(LDFLAGS "-nostdlib -melf_${ELF} -N --eh-frame-hdr ${STRIP_LV} --script=${INSTALL_LOC}/${ARCH}/linker.ld ${PRE_BSS_SIZE} ${INSTALL_LOC}/${ARCH}/lib/crtbegin.o")
 
 set_target_properties(service PROPERTIES LINK_FLAGS "${LDFLAGS}")
 

src/arch/x86_64/linker.ld

@@ -187,6 +187,9 @@ SECTIONS
     LONG (0);
   }
 
+  /** Optional memory hole between memdisk and bss **/
+  . += PRE_BSS_AREA;
+
   .bss ALIGN(0x1000) :
   {
     _BSS_START_ = .;

src/platform/x86_solo5/kernel_start.cpp

@@ -64,6 +64,7 @@ extern "C" {
 
     // Initialize OS including devices
     OS::start(cmdline, mem_size);
+    OS::post_start();
 
     // Starting event loop from here allows us to profile OS::start
     OS::event_loop();

src/platform/x86_solo5/os.cpp

@@ -190,39 +190,17 @@ void OS::halt() {
 }
 
 // Keep track of blocking levels
-static uint32_t* blocking_level = 0;
-static uint32_t* highest_blocking_level = 0;
-
-
-// Getters, mostly for testing
-extern "C" uint32_t os_get_blocking_level() {
-  return *blocking_level;
-}
-extern "C" uint32_t os_get_highest_blocking_level() {
-  return *highest_blocking_level;
-}
+static uint32_t blocking_level = 0;
+static uint32_t highest_blocking_level = 0;
 
 void OS::block()
 {
-  // Initialize stats
-  if (not blocking_level) {
-    blocking_level = &Statman::get()
-      .create(Stat::UINT32, std::string("blocking.current_level")).get_uint32();
-    *blocking_level = 0;
-  }
-
-  if (not highest_blocking_level) {
-    highest_blocking_level = &Statman::get()
-      .create(Stat::UINT32, std::string("blocking.highest")).get_uint32();
-    *highest_blocking_level = 0;
-  }
-
   // Increment level
-  *blocking_level += 1;
+  blocking_level += 1;
 
   // Increment highest if applicable
-  if (*blocking_level > *highest_blocking_level)
-    *highest_blocking_level = *blocking_level;
+  if (blocking_level > highest_blocking_level)
+      highest_blocking_level = blocking_level;
 
   int rc;
   rc = solo5_poll(solo5_clock_monotonic() + 50000ULL); // now + 0.05 ms
@@ -238,7 +216,7 @@ void OS::block()
   }
 
   // Decrement level
-  *blocking_level -= 1;
+  blocking_level -= 1;
 }
 
 extern "C"