U-Boot: Arm64: bootm gets stuck if RANDOMIZE_BASE is disabled

[Ahsan Hussain]

Hello folks,

Any insight would be highly appreciated.

On 7/13/21 2:53 PM, Ahsan Hussain wrote:
>
> On 7/13/21 2:25 PM, Mark Rutland wrote:
>> On Tue, Jul 13, 2021 at 02:15:08PM +0500, Ahsan Hussain wrote:
>>> Hello,
>>>
>>> I'm dumbfounded by a seemingly unrelated early kernel hang/failing 
>>> to boot
>>> when CONFIG_RANDOMIZE_BASE=n is set in kernel and we use FIT uImage. 
>>> I've
>>> verified this behavior on a couple of i.MX8 SoCs (i.MX8M plus and 
>>> i.MX8QXP)
>>> and the results remain consistent.
>>>
>>> I'm able to boot kernel when I use booti command. However when I use 
>>> bootm
>>> to boot a U-Boot fitImage (with kernel and fdt load 
>>> addresses/entrypoint in
>>> .its file same as I used for booti command; also tried disabling 
>>> relocation
>>> for fdt by setting fdt_high=~0UL), the boot gets stuck at "Starting 
>>> kernel
>>> ...". On disabling RANDOMIZE_BASE kconfig in Linux the same fitImage 
>>> is able
>>> to boot.
>> Can you say which address you're trying to load the kernel to?
> At 0xf0000000, towards the end of first DRAM bank which starts at 
> 0x40000000.
>>> I've tried enabling earlycon and U-Boot debug messages in 
>>> common/bootm.c and
>>> arch/arm/lib/bootm.c but found no helpful difference in both boot 
>>> flows.
>>> Please let me know if I'm missing something obvious or where do I start
>>> looking to debug this issue.
>> IIUC, the booti command respects the text_offset from the kernel header,
>> whereas bootm will not. If you have a hard-coded offset, it's possible
>> you're violating the offset the kernel expects, and where the kernel is
>> not relocatable, if can't fix itself up.
>
> A minor correction is that when CONFIG_RANDOMIZE_BASE is _enabled_ the 
> issue is gone. It is only observed when RANDOMIZE_BASE is _disabled_. 
> Both booti and bootm calculate text_offset the same way based on arm64 
> image header->image_size field, in booti_setup() routine from U-Boot 
> arch/arm/lib/image.c.
>
>
> Regards,
> Ahsan
>
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