Cortex A9 MMU

Hello,

many thanks for your replies. I went through the specs. The enabling of the MMU resp. the population of the pagetable has to occur after the SSBL. I presume the SSBL is not part of the problem.

After the SSBL has finished - the baremetal application is started, the latter initilizes the system. The function alt_pt_init(void) enables the MMU and populates the page table, according to the required specifications. 

ALT_STATUS_CODE alt_pt_init (void)
{
    /* Populate the page table with sections (1 MiB regions). */
    ALT_MMU_MEM_REGION_t regions[] = {
        /* Memory area: 1 GiB */
        {
         .va = (void *) 0x00000000,
         .pa = (void *) 0x00000000,
         .size = 0x40000000,
         .access = ALT_MMU_AP_PRIV_ACCESS,			// 1, /*!< Privileged access only 
         .attributes = ALT_MMU_ATTR_WBA,			// 0x13, /*!< Inner/Outer Write-Back, Write Allocate, Shareability determined by [S] bit */
         .shareable = ALT_MMU_TTB_S_NON_SHAREABLE,  // 0,    /*!< Non-Shareable address map */
         .execute = ALT_MMU_TTB_XN_DISABLE,			//  0,
         .security = ALT_MMU_TTB_NS_SECURE},		// 0,

        /* Device area: Everything else */
        {
         .va = (void *) 0x40000000,
         .pa = (void *) 0x40000000,
         .size = 0xc0000000,
         .access = ALT_MMU_AP_PRIV_ACCESS,			// 1, /*!< Privileged access only               */
         .attributes = ALT_MMU_ATTR_DEVICE_NS,		// 0x20, /*!< Device Non-Shareable */
         .shareable = ALT_MMU_TTB_S_NON_SHAREABLE,	// 0   /*!< Non-Shareable address map */
         .execute = ALT_MMU_TTB_XN_ENABLE,			// 1
         .security = ALT_MMU_TTB_NS_SECURE}			// 0,
    };

When the compiled (application.axf) is run in the debugger everything works as it should, however, when the binary (application.bin) is started I get the above message (via - UART Interface): (data abort ...) .

The application.bin is started via UART with the command:

fatload mmc 0:1 0x00100000 application.bin
go 0x00100040;

This procedure works fine as long as the function alt_pt_init() is not executed. 

In summary:

• application.axf can always be exectuded in the debugger (Semi-Hosting).
• application.bin can only be exectuded (using the fatload and go command) when the function alt_pt_init() is not called

Question:

Why does the function  alt_pt_init(void) prevent the application.bin from getting executed? Why can the application.axf still be executed in the debugger?

I am quite sure, that I am missing something rather substantial - and I would be really glad if somebody could provide me with some more tipps.

Many thanks and all the best

Deas

(*for context. The application is supposed to run on a Altera CycloneV containing a Cortex A9.)

Hello,

many thanks for your replies. I went through the specs. The enabling of the MMU resp. the population of the pagetable has to occur after the SSBL. I presume the SSBL is not part of the problem.

After the SSBL has finished - the baremetal application is started, the latter initilizes the system. The function alt_pt_init(void) enables the MMU and populates the page table, according to the required specifications. 

ALT_STATUS_CODE alt_pt_init (void)
{
    /* Populate the page table with sections (1 MiB regions). */
    ALT_MMU_MEM_REGION_t regions[] = {
        /* Memory area: 1 GiB */
        {
         .va = (void *) 0x00000000,
         .pa = (void *) 0x00000000,
         .size = 0x40000000,
         .access = ALT_MMU_AP_PRIV_ACCESS,			// 1, /*!< Privileged access only 
         .attributes = ALT_MMU_ATTR_WBA,			// 0x13, /*!< Inner/Outer Write-Back, Write Allocate, Shareability determined by [S] bit */
         .shareable = ALT_MMU_TTB_S_NON_SHAREABLE,  // 0,    /*!< Non-Shareable address map */
         .execute = ALT_MMU_TTB_XN_DISABLE,			//  0,
         .security = ALT_MMU_TTB_NS_SECURE},		// 0,

        /* Device area: Everything else */
        {
         .va = (void *) 0x40000000,
         .pa = (void *) 0x40000000,
         .size = 0xc0000000,
         .access = ALT_MMU_AP_PRIV_ACCESS,			// 1, /*!< Privileged access only               */
         .attributes = ALT_MMU_ATTR_DEVICE_NS,		// 0x20, /*!< Device Non-Shareable */
         .shareable = ALT_MMU_TTB_S_NON_SHAREABLE,	// 0   /*!< Non-Shareable address map */
         .execute = ALT_MMU_TTB_XN_ENABLE,			// 1
         .security = ALT_MMU_TTB_NS_SECURE}			// 0,
    };

When the compiled (application.axf) is run in the debugger everything works as it should, however, when the binary (application.bin) is started I get the above message (via - UART Interface): (data abort ...) .

The application.bin is started via UART with the command:

fatload mmc 0:1 0x00100000 application.bin
go 0x00100040;

This procedure works fine as long as the function alt_pt_init() is not executed. 

In summary:

• application.axf can always be exectuded in the debugger (Semi-Hosting).
• application.bin can only be exectuded (using the fatload and go command) when the function alt_pt_init() is not called

Question:

Why does the function  alt_pt_init(void) prevent the application.bin from getting executed? Why can the application.axf still be executed in the debugger?

I am quite sure, that I am missing something rather substantial - and I would be really glad if somebody could provide me with some more tipps.

Many thanks and all the best

Deas

(*for context. The application is supposed to run on a Altera CycloneV containing a Cortex A9.)