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From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org
Subject: Re: [PATCH v2 1/1] x86/early_printk: Use __iomem address space for IO
Date: Sun, 11 Oct 2015 21:18:21 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.11.1510112115190.6097@nanos> (raw)
In-Reply-To: <1444400949-103551-1-git-send-email-andriy.shevchenko@linux.intel.com>

Andy,

On Fri, 9 Oct 2015, Andy Shevchenko wrote:
>  #ifdef CONFIG_PCI
>  static void mem32_serial_out(unsigned long addr, int offset, int value)
>  {
> -	u32 *vaddr = (u32 *)addr;
> +	void __iomem *vaddr = (void __iomem *)addr;
>  	/* shift implied by pointer type */
>  	writel(value, vaddr + offset);

This is broken. Assume vaddr = 0x1000 and offset = 1

==>  u32 *vaddr = 0x1000;
==>  vaddr + offset = 0x1004

with your change

==>  void __iomem *vaddr = 0x1000;

==>  vaddr + offset = 0x1001

This comment is there for a reason:
>  	/* shift implied by pointer type */

Thanks,

	tglx

  parent reply	other threads:[~2015-10-11 19:19 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-09 14:29 Andy Shevchenko
2015-10-09 14:35 ` Andy Shevchenko
2015-10-11 19:18 ` Thomas Gleixner [this message]
2015-10-12  8:12   ` Andy Shevchenko
2015-10-12  9:11     ` Thomas Gleixner

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