Is there a limitation of the Length field in the Boot Data to do XIP with QSPI flash?

[SSE-Sak]

Hi NXP team,

I tried XIP from QSPI flash in the custom board that has a i.MX6UL and a external QSPI flash.

I set the IVT and Boot Data as shown below.

    IVT.entry = 0x60002000;    // entry address is within QSPI address range in the CPU memory map.

    BootData.start = 0x60000000;    // Set the start address of QSPI address range to specify XIP.

    BootData.length = 0;    // I think that the length is not required for XIP?

But XIP was not achieved. It seemed to not branch to the IVT.entry and stay in the Boot ROM program.

So I changed the length field to non-zero number for example 0x10000 for trial. Then I succeeded XIP with QSPI. 

At the result of more trial, I found that the length field in the Boot Data with value of equal or greater than 0x20 is required to achieve XIP on QSPI flash.

Although I read Reference Manual and Errata document of i.MX6UL, I didn't find this limitation notice.

Is it described anywhere?

Is this limitation a new Errata?

Thanks.

[Zhiming_Liu]

Hi,

BootData.length here is the size of boot image, it should be the real size of boot image.

Please keep BootData.length non‑zero and set it to the actual image size.

Best Regards,
Zhiming

[SSE-Sak]

Hi NXP TechSupport,



Thank you for responding to my question.

Is my understanding correct that

1. The Boot ROM judges with BootData.length if the boot image exists or not.

2. And does not jump to IVT.entry if the boot image does not exist (i.e. BootData.lengyh is less than 32 bytes).

If this is correct, these Boot ROM's behavior are specific to i.MX6UL? Or is it the same for other SoC?



Best regards,

[Zhiming_Liu]

Hi,

Yes, your understanding are correct. It's similiar for other SOC, the image should be vaild, then ROM handle it.

Best Regards,
Zhiming

[SSE-Sak]

Hi NXP TechSupport,

Thank you for your answer.
However the other custom board which has a i.MX6solo and a external parallel NOR Flash memory connected via EIM that contains application program could run XIP mode although setting BootData.length = 0.
Please let me know why i.MX6solo can run XIP even if BootData.length = 0.

Best regards,
SSE-Sak

[Zhiming_Liu]

Hi,

Does the i.MX6ULL also use EIM?

Best Regards,
Zhiming

[Zhiming_Liu]

If the boot device are different, ROM may handle them differently. However, the issue you mentioned with the i.MX6Solo does indeed go beyond what the manual can explain.

[SSE-Sak]

Hi NXP TechSupport,

Yes the boot device are different.
I was thinking that the BootData.length is only required in non-XIP mode to decide the coping size of the boot image from boot device to DDR or OCRAM.
But, if the BootData.length is also used to determine whether the Boot ROM should jump to IVT.entry, is the i.MX6solo behavior that can boot in XIP mode via EIM with BootData.length = 0 a new errata?

Best regards,

[Zhiming_Liu]

Hi 

Can you share which OS you are using ?  Did you writing "IVT and boot data" by own tools or NXP tool?

Best Regards,
Zhiming

[Zhiming_Liu]

Hi @SSE-Sak 

I need confirm with internal team, not sure if this is a errata or the ROM itself is designed this way


Best Regards,
Zhiming

[SSE-Sak]

Hi NXP TechSupport,

I cannot disclose OS because I'm not in a position to decide sharing details.
I do not use those tools to write IVT and Boot Data. I write IVT and Boot Data as a const table with specific #pragma section in my source code and I write these data to QSPI Flash memory using scatter-loading mechanism so that these section (IVT first) are located in 0x1000 offset from QSPI Flash ROM start address.
So, I don't think OS is relevant.

Best regards,
SSE-Sak

[Zhiming_Liu]

Hi,

I checked with internal team,  doubt that you may use 6Solo chip version may be old,   and on old version chip sample,  ROM code not check that bootdata.length. Please dump 0x00000048 address contents on 6Solo

Best Regards,
Zhiming

[SSE-Sak]

Hi NXP TechSupport,

Sorry for the late reply. Please refer to the dump of the version information below.

Is this version old i.MX6solo? If so, doesn't the ROM code check the bootdata.length for boot image existence?

Best regards,
SSE-Sak

[Zhiming_Liu]

Hi,

Referring register content, ROM code will not check bootdata.length on this chip.

Best Regards,
Zhiming

[SSE-Sak]

Hi NXP TechSupport,

Thank you for the useful information. Please let me know the i.MX6solo version which checks the BootData.length.

Best regards,
SSE-Sak

[Zhiming_Liu · Accepted solution]

Hi @SSE-Sak 

The ROM team has confirmed that they cannot precisely determine whether BootData.length can be detected by identifying the chip version. We can only state that when the content at ROM address 0x48 is 0x14, the ROM will detect BootData.length.

Best Regards,
Zhiming

[SSE-Sak]

Hi NXP TechSupport,

Thank you so much. I understood.

Best regards,
SSE-Sak