[U-Boot] [RFC PATCH 13/15] arm: Implement the 'fake' go command

[Simon Glass]

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 at chromium.org>
---
 arch/arm/lib/bootm.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index 1b6e0ac..28fba19 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();
@@ -225,14 +232,15 @@ 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 *image, 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;
+	kernel_entry = (void (*)(int, int, uint))image->ep;
 
 	s = getenv("machid");
 	if (s) {
@@ -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;
+	if (IMAGE_ENABLE_OF_LIBFDT && image->ft_len)
+		r2 = (unsigned long)image->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;
 }
 
-- 
1.8.2.1