Bootfs got overwritten

Haohui Mai <[email protected]> Thu, 19 Apr 2012 13:40:30 -0500

Newsgroups	gmane.comp.micro-kernel.l4.devel
Message-ID	<[email protected]>

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