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,