From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH 10/12] kexec: arrange for paddr_vmcoreinfo_note() to
 return phys_addr_t
Date: Fri, 29 Apr 2016 16:16:39 +0100
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To: Pratyush Anand <panand@redhat.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, Tony Luck <tony.luck@intel.com>, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, Pawel Moll <pawel.moll@arm.com>, Jonathan Corbet <corbet@lwn.net>, Ian Campbell <ijc+devicetree@hellion.org.uk>, kexec@lists.infradead.org, Fenghua Yu <fenghua.yu@intel.com>, Haren Myneni <hbabu@us.ibm.com>, Rob Herring <robh+dt@kernel.org>, Eric Biederman <ebiederm@xmission.com>, Santosh Shilimkar <ssantosh@kernel.org>, Kumar Gala <galak@codeaurora.org>, Vivek Goyal <vgoyal@redhat.com>
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On Fri, Apr 29, 2016 at 08:36:43PM +0530, Pratyush Anand wrote:
> > +       phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
> > +       return sprintf(buf, "%pa %x\n", &vmcore_base,
> 
> Why do we pass &vmcore_base? Shouldn't it be vmcore_base?

The %pa* printk format specifiers take the value by reference (as
phys_addr_t and friends are not necessarily the same width as a
pointer). Per Documentation/printk-formats.txt:

Physical addresses types phys_addr_t:

        %pa[p]  0x01234567 or 0x0123456789abcdef

        For printing a phys_addr_t type (and its derivatives, such as
        resource_size_t) which can vary based on build options, regardless of
        the width of the CPU data path. Passed by reference.

So the above prints the value of vmcore_base as expected.

Mark.