Re: [PATCH] initrd: Fix virtual/physical mix-up in overwrite test

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 18 Dec 2007 20:52:07 +0100 (CET) Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> On Tue, 18 Dec 2007, Andrew Morton wrote:
> > On Sun, 16 Dec 2007 11:51:00 +0100 (CET) Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On recent kernels, I get the following error when using an initrd:
> > > 
> > > | initrd overwritten (0x00b78000 < 0x07668000) - disabling it.
> > > 
> > > My Amiga 4000 has 12 MiB of RAM at physical address 0x07400000 (virtual
> > > 0x00000000).
> > > The initrd is located at the end of RAM: 0x00b78000 - 0x00c00000 (virtual).
> > > The overwrite test compares the (virtual) initrd location to the (physical)
> > > first available memory location, which fails.
> > > 
> > > This patch converts initrd_start to a page frame number, so it can be safely
> > > compared with min_low_pfn.
> > > 
> > > Before the introduction of discontiguous memory support on m68k
> > > (12d810c1b8c2b913d48e629e2b5c01d105029839), min_low_pfn was just left
> > > untouched by the m68k-specific code (zero, I guess), and everything worked
> > > fine.
> > 
> > breaks x86.
> > 
> > init/main.c: In function 'start_kernel':
> > init/main.c:601: error: implicit declaration of function 'virt_to_pfn'
> > init/main.c:603: warning: format '%08lx' expects type 'long unsigned int', but argument 2 has type 'int'
> 
> Interestingly, virt_to_pfn() exists on a few architectures only :-(
> 
> So what's the correct portable construct to use instead?
> 

I guess page_to_pfn(virt_to_page(addr))?