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Re: [arm] Dom0 hangs after enable KROBE_EVENTS and/or UPROBE_EVENTS in kernel config


On 22/07/2021 22:39, Stefano Stabellini wrote:
On Thu, 22 Jul 2021, Julien Grall wrote:
You can go and edit 76085aff29f585139a37a10ea0a7daa63f70872c to change
from 4K to any multiple of 4K, e.g. 8K, 12K, 16K, 20K. They should all
work the same.

Looking at the boot logs on pastebin I noticed that Xen is not loaded at
a 2MB aligned address. I recommend you change Xen loading address to
0x500200000. And the kernel loading address to 0x500400000.

I am curious to know why you recommend to load at 2MB aligned address. The
Image protocol doesn't require to load a 2MB aligned address. In fact, we add
issue on Juno because the bootloader would load Xen at a 4KB address. UEFI
will also load at a 4KB align address.

It is from empirical evidence :-)


I cannot tell you the exact reason but I saw "strange" problems in the
past that went away after choosing a 2MB alignment. So we settled for
using 2MB in ImageBuilder and we haven't seen any more issues.

It would have been good to report such issue back then so it could have been analyzed and possibly fixed.

However, it could have been anything: a bug in U-Boot not relevant
anymore, a bug in Linux, etc. I don't know for sure.

This is the worrying part. We have a potential bug that no one knows why it happened. Can this be reproduced?


Julien Grall



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