Cortex-M and zImage

[Joachim Eastwood]

On 17 September 2014 08:11, Uwe Kleine-König
<u.kleine-koenig at pengutronix.de> wrote:
> Hello Joachim,
>
> On Tue, Sep 16, 2014 at 10:25:02PM +0200, Joachim Eastwood wrote:
>> I am working on Linux support for the NXP LPC18xx/43xx family of
>> Cortex-M3/M4 microcontrollers. Building zImage for Cortex-M fails
>> with the following two errors:
>> error: arch/arm/boot/compressed/piggy.gzip.o: Conflicting architecture
>> profiles M/A
>> linux/arch/arm/boot/compressed/head.S:794: undefined reference to
>> `CONFIG_PROCESSOR_ID'
>>
>> The last error is easy to fix. But the first about conflicting arch is
>> harder.
> Do you send a patch?

No, I haven't sent a patch to the fix undefined reference since the
conflicting arch stuff prevented zImage from compiling anyways.

> I was able to compile a zImage with the patch below. For the
> "Conflicting architecture profiles" error the most relevant hunk is the
> first. And of course this needs some #ifdefs.

Thanks, I'll give it a try later today.

But is this the way to go?
Adding lots of 'ifdefs CONFIG_CPU_V7M' to compressed/head.S ?

I'll guess Russell have to answer that one.


regards
Joachim Eastwood

> Best regards
> Uwe
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 413fd94b5301..abad996484f1 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -11,7 +11,7 @@
>  #include <linux/linkage.h>
>  #include <asm/assembler.h>
>
> -       .arch   armv7-a
> +       .arch   armv7-m
>  /*
>   * Debugging stuff
>   *
> @@ -114,7 +114,7 @@
>   * sort out different calling conventions
>   */
>                 .align
> -               .arm                            @ Always enter in ARM state
> +               @.arm                           @ Always enter in ARM state
>  start:
>                 .type   start,#function
>                 .rept   7
> @@ -133,7 +133,7 @@ start:
>   THUMB(                .thumb                  )
>  1:
>   ARM_BE8(      setend  be )                    @ go BE8 if compiled for BE8
> -               mrs     r9, cpsr
> +               @mrs    r9, cpsr
>  #ifdef CONFIG_ARM_VIRT_EXT
>                 bl      __hyp_stub_install      @ get into SVC mode, reversibly
>  #endif
> @@ -145,7 +145,7 @@ start:
>                  * FIQs/IRQs (numeric definitions from angel arm.h source).
>                  * We only do this if we were in user mode on entry.
>                  */
> -               mrs     r2, cpsr                @ get current mode
> +               @mrs    r2, cpsr                @ get current mode
>                 tst     r2, #3                  @ not user?
>                 bne     not_angel
>                 mov     r0, #0x17               @ angel_SWIreason_EnterSVC
> @@ -153,7 +153,7 @@ start:
>   THUMB(                svc     0xab            )       @ angel_SWI_THUMB
>  not_angel:
>                 safe_svcmode_maskall r0
> -               msr     spsr_cxsf, r9           @ Save the CPU boot mode in
> +               @msr    spsr_cxsf, r9           @ Save the CPU boot mode in
>                                                 @ SPSR
>                 /*
>                  * Note that some cache flushing and other stuff may
> @@ -366,7 +366,7 @@ dtb_check_done:
>
>  /* Relocate the hyp vector base if necessary */
>  #ifdef CONFIG_ARM_VIRT_EXT
> -               mrs     r0, spsr
> +               @mrs    r0, spsr
>                 and     r0, r0, #MODE_MASK
>                 cmp     r0, #HYP_MODE
>                 bne     1f
> @@ -500,7 +500,7 @@ not_relocated:      mov     r0, #0
>                 mov     r2, r8                  @ restore atags pointer
>
>  #ifdef CONFIG_ARM_VIRT_EXT
> -               mrs     r0, spsr                @ Get saved CPU boot mode
> +               @mrs    r0, spsr                @ Get saved CPU boot mode
>                 and     r0, r0, #MODE_MASK
>                 cmp     r0, #HYP_MODE           @ if not booted in HYP mode...
>                 bne     __enter_kernel          @ boot kernel directly
> @@ -791,7 +791,7 @@ call_cache_fn:      adr     r12, proc_types
>  #ifdef CONFIG_CPU_CP15
>                 mrc     p15, 0, r9, c0, c0      @ get processor ID
>  #else
> -               ldr     r9, =CONFIG_PROCESSOR_ID
> +               @ldr    r9, =CONFIG_PROCESSOR_ID
>  #endif
>  1:             ldr     r1, [r12, #0]           @ get value
>                 ldr     r2, [r12, #4]           @ get mask
>
>> As far as I know zImage on Cortex-M is not supported or not tested.
>>
>> Are there any plans to support zImage on Cortex-M?
>> If so does anyone have an idea how the conflicting arch issue could
>> be solved?
>>
>> btw, building with 'make Image' works fine and I have been running
>> Linux for a while on the NXP LPC4357.
>
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |