Albert,
-----Original Message----- From: Tom Warren [mailto:twarren.nvidia@gmail.com] Sent: Thursday, February 16, 2012 12:46 PM To: u-boot@lists.denx.de Cc: twarren.nvidia@gmail.com; albert.u.boot@aribaud.net; wd@denx.de; sjg@chromium.org; Stephen Warren; Tom Warren Subject: [PATCH] arm: Tegra2: Fix ELDK42 gcc failure with inline asm stack pointer load
The 4.2.2 gcc in the ELDK42 release doesn't like the direct SP load using a constant in tegra2_start. Break it up into 4 loads using mov & orr.
Tested on my Seaboard T20-A03, U-Boot loads and runs OK. Also compiled all tegra2 builds with both gcc 4.2.2 and 4.4.1 OK.
Signed-off-by: Tom Warren twarren@nvidia.com
arch/arm/cpu/armv7/tegra2/ap20.c | 25 ++++++++++++++++++++----- 1 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/arch/arm/cpu/armv7/tegra2/ap20.c b/arch/arm/cpu/armv7/tegra2/ap20.c index 4c44bb3..d2bc0d5 100644 --- a/arch/arm/cpu/armv7/tegra2/ap20.c +++ b/arch/arm/cpu/armv7/tegra2/ap20.c @@ -298,11 +298,26 @@ void tegra2_start(void) writel(0xC0, &pmt->pmt_cfg_ctl);
/*
* If we are ARM7 - give it a different stack. We are about to* start up the A9 which will want to use this one.*/asm volatile("ldr sp, =%c0\n": : "i"(AVP_EARLY_BOOT_STACK_LIMIT));
* If we are ARM7 - give it a different stack. We are about to* start up the A9 which will want to use this one.*//** Note that the 'ldr sp,CONSTANT' version, below, doesn't* work on gcc 4.2.2 (ELDK42), but does on gcc 4.4.1 and above.* The work-around is to use the (ugly) 4-pass mov/orr below.** asm volatile("ldr sp, =%c0\n" : :* "i"(AVP_EARLY_BOOT_STACK_LIMIT));*/asm volatile("mov sp, %0": : "i"(AVP_EARLY_BOOT_STACK_LIMIT & 0xFF));asm volatile("orr sp, %0": : "i"(AVP_EARLY_BOOT_STACK_LIMIT & 0xFF00));asm volatile("orr sp, %0": : "i"(AVP_EARLY_BOOT_STACK_LIMIT & 0xFF0000));asm volatile("orr sp, %0": : "i"(AVP_EARLY_BOOT_STACK_LIMIT & 0xFF000000));start_cpu((u32)_start); halt_avp();
-- 1.7.7.1
This should fix the problem you had with compiling the 6 tegra2 builds w/ELDK42. I've also tested it with gcc 4.4.1 (the one I use every day) and gcc 4.6.1 (used internally @ NVIDIA for Chrome U-Boot builds, etc.). It's an ugly work-around, but it works. Thanks to Simon for the fix, BTW.
Tom