"deactivate" page table flag PG_GLOBAL

- HermitCore is a single-address space OS => CR3 never changed
=> PG_GLOBAL isn't required => set PG_GLOBAL to 0
- could avoid collisions with Linux, which uses PG_GLOBAL for the kernel
  space

hermit/arch/x86/include/asm/page.h

@@ -120,8 +120,16 @@ static inline size_t sign_extend(ssize_t addr, int bits)
 #define PG_PSE			(1 << 7)
 /// Page attribute table
 #define PG_PAT			PG_PSE
-/// Global TLB entry (Pentium Pro and later)
+#if 1
+/* @brief Global TLB entry (Pentium Pro and later)
+ *
+ * HermitCore is a single-address space operating system
+ * => CR3 never changed => The flag isn't required for HermitCore
+ */
+#define PG_GLOBAL		0
+#else
 #define PG_GLOBAL		(1 << 8)
+#endif
 /// This table is a self-reference and should skipped by page_map_copy()
 #define PG_SELF			(1 << 9)
 

hermit/arch/x86/kernel/entry.asm

@@ -160,10 +160,10 @@ start64:
 
     ; remap kernel
     mov rdi, kernel_start
-    shr rdi, 18               ; (edi >> 21) * 8 (index for boot_pgd)
+    shr rdi, 18       ; (edi >> 21) * 8 (index for boot_pgd)
     add rdi, boot_pgd
     mov rax, [base]
-    or rax, 0x183
+    or rax, 0x83      ; PG_GLOBAL isn't required because HermitCore is a single-address space OS
     xor rcx, rcx
 Lremap:
     mov QWORD [rdi], rax