[PATCH master 1/2] ARM: document PBL barebox memory layout

[Ahmad Fatoum]

Apparently, we have an overlap between ramoops/barebox proper
and the early malloc area. Before fixing that, let's add a diagram
explaining the current state of affairs.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 arch/arm/include/asm/barebox-arm.h | 36 ++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
index 4d70360b9121..30834233fb96 100644
--- a/arch/arm/include/asm/barebox-arm.h
+++ b/arch/arm/include/asm/barebox-arm.h
@@ -52,6 +52,42 @@ static inline void arm_fixup_vectors(void)
 
 void *barebox_arm_boot_dtb(void);
 
+/*
+ *  ----------------------------- endmem ------------------------------
+ *                                   ↑
+ *	        OPTEE_SIZE (depends on CONFIG_OPTEE_SIZE)
+ *                                   ↓
+ *  ------------------------- arm_mem_optee() -------------------------
+ *                                   ↑
+ *                                 SZ_32K
+ *                                   ↓
+ *  ------------------------ arm_mem_scratch() ------------------------
+ *                                   ↑
+ *                               STACK_SIZE
+ *                                   ↓
+ *  ------------------------- arm_mem_stack() -------------------------
+ *                                   ↑
+ *            PAGE_SIZE (depends on CONFIG_STACK_GUARD_PAGE)
+ *                                   ↓
+ *  ----------------------- arm_mem_guard_page() ----------------------
+ *                                   ↑
+ *                       ARM_EARLY_PAGETABLE_SIZE
+ *                                   ↓
+ *  ------------ arm_mem_ttb() / arm_mem_early_malloc_end() ------------
+ *                                   ↑                          ↑
+ *                     CONFIG_FS_PSTORE_RAMOOPS_SIZE         SZ_128K
+ *                     (depends on FS_PSTORE_RAMOOPS)           |
+ *                                   |                          ↓
+ *                                   | ------ arm_mem_early_malloc() ---
+ *                                   ↓
+ *  ------------------------- arm_mem_ramoops() ------------------------
+ *                                   ↑
+ *                   (barebox uncompressed image size
+ *                       + BSS) rounded to SZ_1M
+ *                                   ↓
+ *  ---------------------- arm_mem_barebox_image() ---------------------
+ */
+
 static inline unsigned long arm_mem_optee(unsigned long endmem)
 {
 	return endmem - OPTEE_SIZE;
-- 
2.39.2