RE: [PATCH] a new UniCore32 arch-dependent patch for linux-2.6.37-rc1

["Guan Xuetao" <guanxuetao@mprc.pku.edu.cn>]

> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@arndb.de]
> Sent: Tuesday, November 30, 2010 11:27 PM
> To: Guan Xuetao
> Cc: 'Greg KH'; 'Andrew Morton'; 'Linus Torvalds'; linux-
> kernel@vger.kernel.org; linux-arch@vger.kernel.org
> Subject: Re: [PATCH] a new UniCore32 arch-dependent patch for linux-
> 2.6.37-rc1
> 
> On Tuesday 30 November 2010, Guan Xuetao wrote:
> > > On Saturday 27 November 2010, Guan Xuetao wrote:
> > > > >
> > > > > In what way does the architecture enforce this? What are the
> > > > > contents of this page? Can you make it an actual VDSO rather
> > > > > than a magic page that sits in the user address space?
> > > > Page table is created for vector page and exceptions entry stub.
> > > > However, vector page is not in the user address space.
> > >
> > > Interesting. So if it's not mapped into user space, why do you even
> > > need to have the vectors at a specific page? I think ARM only maps
> > > it to the high page because that page is shared to user space, while
> > > most architectures just have their interrupt vectors in the linar
> > > mapping, since the hardware typically uses the physical address to
find it.
> >
> > In UniCore-32, when MMU enabled, vector page address is virtual address.
> 
> Ok. I see.
> 
> The arch_exit_mmap() and arch_setup_additional_pages() functions seems
> to refer to how ARM maps this page into user space as well, you should
> probably change that.
Vector page is also used as kuser page, so arch_setup_additional_pages need
to 
Map it into user space.

> 
> I've finished the second half of the code review now, I'll follow up with
an
> email but drop the personal Cc to everyone besides us, in case people are
> getting bored from the discussion by now ;-)
Thanks again.

Guan Xuetao