fix LLVM

+ Anything extern is right out as LLVM doesn't produce correct code for
  them. Maybe if I added some extra attributes but I'm skeptical.
  Replaced with static variables and getters/setters.

+ Inline ASM is apparently a bit buggy, so use an assembly stub when jumping to init.

+ Minimize work done in main() to minimize chance of LLVM doing something silly.
  Still not 100% certain that I shouldn't just write the main() as an assembly stub
  in arch/riscv64 to be absolutely sure everything works as intended.

+ Make .kernel.start section SHF_ALLOC, otherwise lld complains about
  pc-relative addressing

Probably some other stuff as well that I'm forgetting right now. But at least with
LLVM14 LTO seems to work, which is pretty cool?

1 files changed, 11 insertions, 19 deletions

diff --git a/src/main.c b/src/main.c
index f3c5e17..12d8514 100644
--- a/src/main.c
+++ b/src/main.c
@@ -61,6 +61,15 @@ __noreturn void kernel(void *fdt, uintptr_t load_addr, struct vmem *d)
 	/* we should be in kernelspace, so use the virtual address of our FDT. */
 	fdt = __va(fdt);
 
+	/** @todo some kind of lottery? */
+	pm_t ram_base = __fdt_ram_base(fdt);
+	pm_t ram_size = __fdt_ram_size(fdt);
+	set_ram_base(ram_base);
+	set_ram_size(ram_size);
+	set_load_addr(load_addr);
+
+	init_dbg(fdt);
+
 	/* start up debugging in kernel IO */
 	setup_io_dbg(d);
 
@@ -102,27 +111,10 @@ __noreturn void main(unsigned long hart, void *fdt, uintptr_t load_addr)
 	/* we have our own ways to get the current hart when we need it, but we
 	 * have to get the function signature right */
 	(void)hart;
-
-	/* dbg uses direct mapping at this point, useful for early init asserts
-	 * and so on */
-	init_dbg(fdt);
-
-	/** @todo some kind of lottery? */
-	pm_t ram_base = __fdt_ram_base(fdt);
-	pm_t ram_size = __fdt_ram_size(fdt);
-	set_ram_base(ram_base);
-	set_ram_size(ram_size);
-	set_load_addr(load_addr);
-
 	init_mem(fdt);
 
-	/* we don't have any debug output just yet but still */
-	/* also this is I guess more of an architecture limitation, should the
-	 * whole of main() just be moved to arch? */
-	assert(is_aligned(load_addr, order_size(MM_O1)));
-
-	struct vmem *d = init_mapping();
-	to_kernelspace(fdt, load_addr, d, ram_base);
+	struct vmem *d = init_mapping(load_addr);
+	to_kernelspace(fdt, load_addr, d, 0);
 	unreachable();
 }