From d5f5d91b8488b220a51aed3b63aa9de26c1ac73c Mon Sep 17 00:00:00 2001
From: Jessica Clarke <jrtc27@jrtc27.com>
Date: Wed, 29 Apr 2020 03:24:21 +0100
Subject: Support --without-payload for OpenSBI fw_jump-style booting (#186)

We expect the firmware to load the external payload at the second
megapage, and that there is space to put the filtered FDT at 0x2200000
past the start of memory. With a default MEM_START of 0x80000000, this
matches the standard OpenSBI values for FW_JUMP_ADDR and
FW_JUMP_FDT_ADDR of 0x80400000/0x80200000 (RV32/RV64) and 0x82200000
respectively, so payloads linked for one should work with the other.
---
 bbl/bbl.c     | 14 +++++++++++---
 bbl/bbl.mk.in | 12 ++++++++++--
 2 files changed, 21 insertions(+), 5 deletions(-)

(limited to 'bbl')

diff --git a/bbl/bbl.c b/bbl/bbl.c
index ce1be95..3b92fc1 100644
--- a/bbl/bbl.c
+++ b/bbl/bbl.c
@@ -9,7 +9,14 @@
 #include "fdt.h"
 #include <string.h>
 
+#ifdef BBL_PAYLOAD
 extern char _payload_start, _payload_end; /* internal payload */
+# define PAYLOAD_START &_payload_start
+# define PAYLOAD_END ROUNDUP((uintptr_t)&_payload_end, MEGAPAGE_SIZE)
+#else
+# define PAYLOAD_START (void*)(MEM_START + MEGAPAGE_SIZE)
+# define PAYLOAD_END (void*)(MEM_START + 0x2200000)
+#endif
 static const void* entry_point;
 long disabled_hart_mask;
 
@@ -23,8 +30,9 @@ static uintptr_t dtb_output()
    * address. The kernel's virtual mapping begins at its load address,
    * thus mandating device-tree is in physical memory after the kernel.
    */
-  uintptr_t end = kernel_end ? (uintptr_t)kernel_end : (uintptr_t)&_payload_end;
-  return (end + MEGAPAGE_SIZE - 1) / MEGAPAGE_SIZE * MEGAPAGE_SIZE;
+  uintptr_t end = kernel_end ? ROUNDUP((uintptr_t)kernel_end, MEGAPAGE_SIZE)
+                             : (uintptr_t)PAYLOAD_END;
+  return end;
 }
 
 static void filter_dtb(uintptr_t source)
@@ -123,6 +131,6 @@ void boot_loader(uintptr_t dtb)
 #endif
   mb();
   /* Use optional FDT preloaded external payload if present */
-  entry_point = kernel_start ? kernel_start : &_payload_start;
+  entry_point = kernel_start ? kernel_start : PAYLOAD_START;
   boot_other_hart(0);
 }
diff --git a/bbl/bbl.mk.in b/bbl/bbl.mk.in
index b0ef476..a35e783 100644
--- a/bbl/bbl.mk.in
+++ b/bbl/bbl.mk.in
@@ -4,7 +4,6 @@ bbl_subproject_deps = \
 	util \
   softfloat \
   machine \
-  dummy_payload \
 
 bbl_hdrs = \
   bbl.h \
@@ -13,13 +12,22 @@ bbl_c_srcs = \
   logo.c \
 
 bbl_asm_srcs = \
-  payload.S \
   raw_logo.S \
 
+ifeq (@BBL_PAYLOAD@,dummy_payload)
+bbl_subproject_deps += \
+  dummy_payload
+endif
+
+ifneq (@BBL_PAYLOAD@,no)
+bbl_asm_srcs += \
+  payload.S
+
 payload.o: bbl_payload
 
 bbl_payload: $(BBL_PAYLOAD)
 	if $(READELF) -h $< 2> /dev/null > /dev/null; then $(OBJCOPY) -O binary --set-section-flags .bss=alloc,load,contents $< $@; else cp $< $@; fi
+endif
 
 raw_logo.o: bbl_logo_file
 
-- 
cgit v1.1