From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3C338DAC.EC325F3@earthlink.net> Date: Wed, 02 Jan 2002 22:46:04 +0000 From: Joseph A Knapka MIME-Version: 1.0 Subject: Re: Maximum physical memory on i386 platform References: <20020102222026.69416.qmail@web12304.mail.yahoo.com> <3C33B37E.4050604@zytor.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: "H. Peter Anvin" Cc: Ravi K , kernelnewbies@nl.linux.org, linux-mm@kvack.org List-ID: "H. Peter Anvin" wrote: > > Ravi K wrote: > > > Hi, > > The configuration help for HIGHMEM feature on i386 > > platform states that 'Linux can use up to 64 Gigabytes > > of physical memory on x86 systems'. I see a problem > > with this: > > - page structures needed to support 64GB would take > > up 1GB memory (64 bytes per page of size 4k) > > 64GB is physical memory, not virtual memory. And at approx. 64 bytes per strct page in mem_map, that's 1G worth of page structs, which is Ravi's point. Cheers, -- Joe "I should like to close this book by sticking out any part of my neck which is not yet exposed, and making a few predictions about how the problem of quantum gravity will in the end be solved." --- Physicist Lee Smolin, "Three Roads to Quantum Gravity" -- 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/