From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id B604667C02 for ; Mon, 6 Nov 2006 14:17:32 +1100 (EST) Subject: fixup_bigphys_addr and ioremap64 question From: Benjamin Herrenschmidt To: linuxppc-dev list Content-Type: text/plain Date: Mon, 06 Nov 2006 14:17:25 +1100 Message-Id: <1162783045.28571.283.camel@localhost.localdomain> Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , While merging io.h between 32 and 64 bits arch/powerpc, I stumbled upon this little gem :-) So we have these: - If CONFIG_PHYS_64BIT is not set, nothing special. phys_addr_t is defined to be 32 bits. - If it is set however, we have phys_addr_t defined to be 64 bits in asm-ppc/mmu.h. So why do we have both ioremap and ioremap64 knowing that the former is defined to take a phys_addr_t argument ? Currently, we have both, with the only difference being that ioremap calls ioremap64 but also passes the argument through a fixup_bigphys_addr() function first. It took me a while to find it ... it's not defined in generic code but in platform code (ugh !). In fact, the only version of it we have in arch/powerpc is in the 85xx support and does: phys_addr_t fixup_bigphys_addr(phys_addr_t addr, phys_addr_t size) { return addr; }; So here's my question: Is it, as I think, some old mecanism that was useful when ioremap didn't take a phys_addr_t argument and resources didn't have 64 bits fields and thus we had a way to "remap" IOs from a 32 bits space into a 64 bits space in a platform specific way ? Now, the big question is: do we still need that ? If, as I expect, the answer is no, then I'll just remove it. I'll also remove ioremap64 from arch/powerpc since ioremap can take a 64 bits value directly. Now, if the answer is yes, then I'll turn it into a ppc_md. call since it its current form, it's just broken. Ben.