From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m-net.arbornet.org (m-net.arbornet.org [209.142.209.161]) by kvack.org (8.8.7/8.8.7) with ESMTP id FAA30746 for ; Mon, 5 Apr 1999 05:38:49 -0400 Date: Mon, 5 Apr 1999 05:12:50 -0400 (EDT) From: Amol Mohite Subject: Re: Somw questions [ MAYBE OFFTOPIC ] In-Reply-To: <19990402113555.F9584@uni-koblenz.de> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: ralf@uni-koblenz.de Cc: linux-mm@kvack.org List-ID: > A NULL pointer is just yet another invalid address. There is no special > test for a NULL pointer. Most probably for example (char *)0x12345678 will > be invalid as a pointer as well and treated the same. The CPU detects this > when the TLB doesn't have a translation valid for the access being attempted. > Yes but how does it know it is a null pointer ? On that note, when c does not allow u to dereference a void pointer , is this compiler doing the trick ? Ok , about the expand down attribute, thats how 32 bit windows does it, so i was wondering if linux also does the same. 16 bit windows accesses a null pointer with a 0: descriptor. Apparently intel allows u to load a 0 but not dererence it. -- To unsubscribe, send a message with 'unsubscribe linux-mm my@address' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/