Re: Fatal trap 12: page fault on Acer Chromebook 720 (peppy)

On Wed, 29 Aug 2018 11:21:05 +0200
Michael Gmelin <freebsd_at_grem.de> wrote:

> On Sun, 26 Aug 2018 16:04:35 +0300
> Konstantin Belousov <kostikbel_at_gmail.com> wrote:
> 
> > On Sat, Aug 25, 2018 at 07:21:28PM +0200, Michael Gmelin wrote:  
> > > Now, with the patch applied correctly, the machine actually boots.
> > > 
> > > Before calling init_ops.mp_bootaddress in
> > > getmemsize (machdep.c), physmap looks like this:
> > > 
> > > physmap_idx: 8
> > > i mem atop
> > > 0 0x0 0x0
> > > 1 0x30000 0x30
> > > 2 0x40000 0x40
> > > 3 0x9e400 0x9e
> > > 4 0x100000 0x100
> > > 5 0xf00000 0xf00
> > > 6 0x1000000 0x1000
> > > 7 0x7bf7a000 0x7bf7a
> > > 8 0x100000000 0x100000
> > > 9 0x100600000 0x100600
> > > 10 0x0 0x0
> > > 
> > > With your patch, it looks like this now
> > > (after calling getmemsize)
> > > 
> > > 0 0x0 0x0
> > > 1 0x30000 0x30
> > > 2 0x40000 0x40
> > > 3 0x9e400 0x9e
> > > 4 0x100000 0x100
> > > 5 0xf00000 0xf00
> > > 6 0x1000000 0x1000
> > > 7 0x7bf77000 0x7bf77
> > > 8 0x100000000 0x100000
> > > 9 0x100600000 0x100600
> > > 10 0x0 0x0
> > > PAGETABLES is 0x7bf77000
> > > 
> > > So I guess this means that the gap is now at the last three pages
> > > of [0x1000, 0x7bf7a[.
> > > 
> > > If this is what was intended, I guess it's good, as the machine
> > > boots okay now.    
> > 
> > It triggered the new code to chomp at the end of the suitable range,
> > instead of the start. Anyway, to do that, it must evaluated the
> > start of the range as intersecting with the kernel text, which I
> > interpret as success.
> > 
> > I put a review with the change at D16907.
> >   
> > > 
> > > Sorry again for the extra roundtrip, the patched file was simply
> > > in the wrong path.    
> > 
> > No problem.  
> 
> Just to close the loop on this: This was fixed in r338858, thanks to
> kib_at_ for analyzing the problem and creating a patch and to jhb_at_ for
> reviewing it.
> 

The actual revision this was fixed in is r338356
(https://svnweb.freebsd.org/base?view=revision&revision=338356), I
tested r338358 (world+kernel) to verify the fix.

Best,
Michael

-- 
Michael Gmelin