On Fri, Feb 28, 2014 at 09:21:40AM +0100, Philippe Rétornaz wrote: > Le 27/02/2014 21:36, Sascha Hauer a écrit : > >On Thu, Feb 27, 2014 at 03:03:45PM +0100, Philippe Rétornaz wrote: > >>+lwl-y += lowlevel.o > >>+obj-y += mx31moboard.o > >>diff --git a/arch/arm/boards/mx31moboard/env/boot/net b/arch/arm/boards/mx31moboard/env/boot/net > >>new file mode 100644 > >>index 0000000..e81f2cd > >>--- /dev/null > >>+++ b/arch/arm/boards/mx31moboard/env/boot/net > >>@@ -0,0 +1,3 @@ > >>+#!/bin/sh > >>+ > >>+# No network card support on this board > > > >Are you sure you want to drop this? You could attach a USB ethernet > >dongle. > > Ok, I will remove this file. > > >>diff --git a/arch/arm/boards/mx31moboard/env/boot/sd b/arch/arm/boards/mx31moboard/env/boot/sd > >>new file mode 100644 > >>index 0000000..f96633f > >>--- /dev/null > >>+++ b/arch/arm/boards/mx31moboard/env/boot/sd > >>@@ -0,0 +1,18 @@ > >>+#!/bin/sh > >>+ > >>+if [ "$1" = menu ]; then > >>+ boot-menu-add-entry "$0" "SD Boot" > >>+ exit > >>+fi > >>+ > >>+global.bootm.image=/mnt/sd/boot/zImage > >>+ > >>+if [ -e /mnt/sd/boot/oftree ]; then > >>+ global.bootm.oftree=/mnt/sd/boot/oftree > >>+fi > >>+ > >>+if [ -e /mnt/sd/boot/initrd.img ]; then > >>+ global.bootm.initrd=/mnt/sd/boot/initrd.img > >>+fi > >>+ > >>+global.linux.bootargs.dyn.root="root=/dev/mmcblk0p1 rootwait" > > > >Consider using bootloader spec entries, see > >http://www.freedesktop.org/wiki/Specifications/BootLoaderSpec/ > >Basically you put a config file under /loader/entries/ in your rootfs. > >The config file describes where your kernel/initrd/oftree is. Under > >barebox you just have to 'boot mci0' without further configuration. > > Seems nice, I'll have a look at it. > > >>+void __bare_init __naked barebox_arm_reset_vector(void) > >>+{ > >>+ uint32_t r; > >>+ > >>+ arm_cpu_lowlevel_init(); > >>+ > >>+ /* Enable IPU Display interface */ > >>+ writel(1 << 6, MX31_IPU_CTRL_BASE_ADDR); > >>+ > >>+ writel(0x074B0BF5, MX31_CCM_BASE_ADDR + MX31_CCM_CCMR); > >>+ > >>+ asm volatile("1:\n\t" > >>+ "SUBS %0, %0, #1 \n\t" > >>+ "BNE 1b \n\t" > >>+ : : "r" (0x4000) : "cc"); > > > >You can write a delay loop in c with: > > > > volatile int c; > > > > for (c = 0; c < 0x4000; c++) > > Well, no, at least not on my toolchain. Because the volatile ask gcc to > not optimize the variable, it then put it on the stack. But the stack > pointer is not yet initialized, so it crashes. I've tried with a > barrier() instead of the volatile, but it leads to the same assembly > (which is not surprising). Here is the compiled code with your suggestion: > > ldr r2, .L9+8 > b .L2 > .L3: > ldr r3, [sp, #4] > add r3, r3, #1 > str r3, [sp, #4] > .L2: > ldr r3, [sp, #4] > cmp r3, r2 > ble .L3 > > With L9+8: > .word 16383 > > But the stack pointer is initialised only in barebox_arm_entry() which > is called later. So I decided that a two instructions assembly loop was > the simplest solution. This may happen because the function gets too complex and gcc starts using the stack in this case. Try rewriting the lowlevel stuff as: static void __noinline mx31_moboard_startup(void) { /* Put setup here */ } void __bare_init __naked barebox_arm_reset_vector(void) { arm_cpu_lowlevel_init(); arm_setup_stack(MX31_IRAM_BASE_ADDR + MX31_IRAM_SIZE - 12); mx31_moboard_startup(); } With this you can use the stack and should be on the safe side. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
