From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3C6ACC76.6A3D3A36@scs.ch> Date: Wed, 13 Feb 2002 21:28:38 +0100 From: Martin Maletinsky MIME-Version: 1.0 Subject: __pa() vs. virt_to_phys() Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: kernelnewbies@nl.linux.org, linux-mm@kvack.org List-ID: Hi, Is there any reason to use __pa() rather than virt_to_phys() or vice versa? On i386 virt_to_phys() is just a function that returns the value returned by __pa(); on Alpha virt_to_phys() is a function that subtracts IDENT_ADDR from the argument, whereas __pa() is a macro that subtracts PAGE_OFFSET from its argument - however PAGE_OFFSET and IDENT_ADDR expand to the same value; on Sparc virt_to_phys() is a macro that expands to __pa(). So the two things look to be pretty much the same on different platforms - is there any reason for having __pa() as well as virt_to_phys(), and which one is to be used by device drivers? thanks for your help regards Martin -- Supercomputing System AG email: maletinsky@scs.ch Martin Maletinsky phone: +41 (0)1 445 16 05 Technoparkstrasse 1 fax: +41 (0)1 445 16 10 CH-8005 Zurich -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/