From bce1b92aa11fc7dadae19452e9ff84c33a4b0c9a Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Wed, 19 Jun 2013 21:15:10 -0700
Subject: arm: Implement the 'fake' go command

Implement this feature on ARM for tracing.

It would be nice to have generic bootm support so that it is easily
implemented on any arch.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Albert ARIBAUD <albert.u.boot@aribaud.net>

diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index 1b6e0ac..b22fbc9 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -68,12 +68,19 @@ void arch_lmb_reserve(struct lmb *lmb)
 		    gd->bd->bi_dram[0].start + gd->bd->bi_dram[0].size - sp);
 }
 
-static void announce_and_cleanup(void)
+/**
+ * announce_and_cleanup() - Print message and prepare for kernel boot
+ *
+ * @fake: non-zero to do everything except actually boot
+ */
+static void announce_and_cleanup(int fake)
 {
-	printf("\nStarting kernel ...\n\n");
+	printf("\nStarting kernel ...%s\n\n", fake ?
+		"(fake run for tracing)" : "");
 	bootstage_mark_name(BOOTSTAGE_ID_BOOTM_HANDOFF, "start_kernel");
 #ifdef CONFIG_BOOTSTAGE_FDT
-	bootstage_fdt_add_report();
+	if (flag == BOOTM_STATE_OS_FAKE_GO)
+		bootstage_fdt_add_report();
 #endif
 #ifdef CONFIG_BOOTSTAGE_REPORT
 	bootstage_report();
@@ -225,12 +232,13 @@ static void boot_prep_linux(bootm_headers_t *images)
 }
 
 /* Subcommand: GO */
-static void boot_jump_linux(bootm_headers_t *images)
+static void boot_jump_linux(bootm_headers_t *images, int flag)
 {
 	unsigned long machid = gd->bd->bi_arch_number;
 	char *s;
 	void (*kernel_entry)(int zero, int arch, uint params);
 	unsigned long r2;
+	int fake = (flag & BOOTM_STATE_OS_FAKE_GO);
 
 	kernel_entry = (void (*)(int, int, uint))images->ep;
 
@@ -243,14 +251,15 @@ static void boot_jump_linux(bootm_headers_t *images)
 	debug("## Transferring control to Linux (at address %08lx)" \
 		"...\n", (ulong) kernel_entry);
 	bootstage_mark(BOOTSTAGE_ID_RUN_OS);
-	announce_and_cleanup();
+	announce_and_cleanup(fake);
 
 	if (IMAGE_ENABLE_OF_LIBFDT && images->ft_len)
 		r2 = (unsigned long)images->ft_addr;
 	else
 		r2 = gd->bd->bi_boot_params;
 
-	kernel_entry(0, machid, r2);
+	if (!fake)
+		kernel_entry(0, machid, r2);
 }
 
 /* Main Entry point for arm bootm implementation
@@ -270,13 +279,13 @@ int do_bootm_linux(int flag, int argc, char *argv[], bootm_headers_t *images)
 		return 0;
 	}
 
-	if (flag & BOOTM_STATE_OS_GO) {
-		boot_jump_linux(images);
+	if (flag & (BOOTM_STATE_OS_GO | BOOTM_STATE_OS_FAKE_GO)) {
+		boot_jump_linux(images, flag);
 		return 0;
 	}
 
 	boot_prep_linux(images);
-	boot_jump_linux(images);
+	boot_jump_linux(images, flag);
 	return 0;
 }
 
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