linux-kernel - %pa format specifier issues

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Message-ID: <51369964.6040101@linux.vnet.ibm.com>
Date:	Tue, 05 Mar 2013 17:18:28 -0800
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Stepan Moskovchenko <stepanm@...eaurora.org>,
	Rob Landley <rob@...dley.net>,
	George Spelvin <linux@...izon.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Andrei Emeltchenko <andrei.emeltchenko@...el.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>
Subject: %pa format specifier issues

I went to go use the shiny new %pa specifier:

void test_printk_pa(void)
{
        phys_addr_t p = 0x1234;
        printk("p: %pa\n", p);
}

but gcc is spewing out warnings at me:

> arch/x86/mm/physaddr.c: In function ‘test_printk_pa’:
> arch/x86/mm/physaddr.c:95:2: warning: format ‘%p’ expects argument of type ‘void *’, but argument 2 has type ‘phys_addr_t’ [-Wformat]

I assume that's because gcc doesn't know about '%pa', and just assumes
it's a plain '%p'.  Should we be turning these warnings off somehow?

Plus when I actually go to run it, vsnprintf() crashes the kernel, which
usually happens if printk()'s format doesn't match the size of its
arguments.

Am I doing something really stupid here?

This is using a 32-bit i386 kernel.

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