Hello Vadzim,
On Mon, 19 Oct 2015 19:40:14 +0300, Vadzim Dambrouski <pftb...@gmail.com> wrote:
> If you enable CONFIG_SEMIHOSTING for STM32F429 target, you will get compile
> error looking like this:
>
> arch/arm/lib/semihosting.c: In function 'smh_read':
> {standard input}: Assembler messages:
> {standard input}:34: Error: invalid swi expression
> {standard input}:34: Error: value of 1193046 too large for field of 2 bytes
> at 0
> scripts/Makefile.build:277: recipe for target 'arch/arm/lib/semihosting.o'
> failed
>
> The source of the problem is "svc #0x123456" instruction. This instruction
> can not be encoded using Thumb2 instruction set used by ARMv7M CPUs.
> ARM documentation suggests using "bkpt #0xAB" instruction instead [1].
> This patch fixes compile errors and adds support for semihosting for
> STM32F429 or any other ARMv7M target.
> This change was sested on STM32F429-DISCOVERY board using OpenOCD and
> "smhload" u-boot command.
>
> [1]
> http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0471c/Bgbjhiea.html
>
> Signed-off-by: Vadzim Dambrouski <pftb...@gmail.com>
> ---
>
> arch/arm/lib/semihosting.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/lib/semihosting.c b/arch/arm/lib/semihosting.c
> index c3e964e..ed5e8e4 100644
> --- a/arch/arm/lib/semihosting.c
> +++ b/arch/arm/lib/semihosting.c
> @@ -31,6 +31,8 @@ static noinline long smh_trap(unsigned int sysnum, void
> *addr)
> register long result asm("r0");
> #if defined(CONFIG_ARM64)
> asm volatile ("hlt #0xf000" : "=r" (result) : "0"(sysnum), "r"(addr));
> +#elif defined(CONFIG_CPU_V7M)
> + asm volatile ("bkpt #0xAB" : "=r" (result) : "0"(sysnum), "r"(addr));
> #else
> /* Note - untested placeholder */
> asm volatile ("svc #0x123456" : "=r" (result) : "0"(sysnum), "r"(addr));
> --
> 2.6.1
>
Applied to u-boot-arm/master, thanks!
Amicalement,
--
Albert.
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