Re: kernel page 0

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 28/11/2016 à 09:57, Masanobu SAITOH a écrit :
>   Hello.
> 
>   Thank you for all of your work.
> 
>   Do you remember the following mail?
> 
>> http://mail-index.netbsd.org/port-i386/2016/01/15/msg003432.html
> 
>   You've fixed a lot of problem on x86, so I suspected that the above
> problem might be fixed. Today, I tried again and I knew the problem
> still exist. I can't fix it because I'm not familiar with vm&pmap :-<
> 
>   As you know, when we fix this problem, we will see a lot of unknown
> bugs. It's important.
> 
>   Thanks.
> 

There is no problem in the amd64 and i386 maps, and NULL is never readable.
In fact, you just forgot to add a {x,z,o,d,u,r,c,s,m} in your "x/l 0x0"
command.

Having only "l" does not actually read anything. With a proper command,
you can see that reading NULL indeed panics the kernel, as expected.