Bootfs got overwritten

[Haohui Mai]

What is more interesting is that only that page is overwritten: The page before and after it stays the same.

~Haohui

On Apr 19, 2012, at 1:40 PM, Haohui Mai wrote:

> Hi,
> 
> I'm encountering a problem where the memory region of BOOTFS of L4Re got overwritten. Interestingly, the page is overwritten by things in the bootfs.
> 
> Here are the physical memory mapping set up by BOOTFS:
> 
> ...
>  BOOTFS: [2227000-23297b8] [C:506000] rtc
>  BOOTFS: [232a000-26d5411] [C:507000] mag
>  BOOTFS: [26d6000-2848a94] [C:508000] fb-drv
>  BOOTFS: [129d000-129daa4] [C:509000] vandroid-x86.cfg
>  BOOTFS: [126b000-126b3b7] [C:50a000] x86-legacy.devs
> …
> 
> The page 0x2239000 (which belongs to rtc) is magically overwritten by the first page of x86-legacy.devs. I confirmed it with both JDB and QEMU monitor.
> 
> I'm running the newest snapshot of L4Re / L4Android on top of the UP version L4.Fiasco kernel.
> 
> What would be the best approach to debug the problem? is it there a way to mark the whole BOOTFS as read-only so that I can figure out what's going on?
> 
> Thanks!
> 
> ~Haohui