From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Use of __pa() with CONFIG_NONLINEAR From: Dave Hansen Content-Type: text/plain Message-Id: <1090965630.15847.575.camel@nighthawk> Mime-Version: 1.0 Date: Tue, 27 Jul 2004 15:00:30 -0700 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm Cc: Linux Kernel Mailing List List-ID: So, for CONFIG_NONLINEAR, we introduce a new indirection layer for virtual to physical conversions (and the inverse as well). Our implementation uses some data structures to do this (patch is here: http://lwn.net/Articles/79124/), and the side-effect is that we can't use __pa() or __va() until after the initialization has run, which is early in setup_arch(). But, there are quite a few things that obviously need physical addresses earlier than that, such as cr3 initialization at compile-time. So, in Dave McCracken's patch, he introduced a new function: __boot_pa() that does what the old __pa() did. This is the largest and hardest to maintain part of the CONFIG_NONLINEAR patch at this point, and I'd love to start merging bits of it back in. Would anybody object to a patch that just does this for a bunch of architectures? --- include/asm-i386/page.h.orig 2004-07-27 14:31:09.000000000 -0700 +++ include/asm-i386/page.h 2004-07-27 14:31:36.000000000 -0700 @@ -128,8 +128,10 @@ static __inline__ int get_order(unsigned #define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET) #define VMALLOC_RESERVE ((unsigned long)__VMALLOC_RESERVE) #define MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE) -#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET) -#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET)) +#define __boot_pa(x) ((unsigned long)(x)-PAGE_OFFSET) +#define __boot_va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET)) +#define __pa(x) __boot_pa(x) +#define __va(x) __boot_va(x) #define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT) #ifndef CONFIG_DISCONTIGMEM #define pfn_to_page(pfn) (mem_map + (pfn)) We will, of course be overriding __{v,p}a() for any architectures that we do nonlinear with, later on. The only other thing I can think of is to make __pa() effectively the boot-time, simple one, and make virt_to_phys() the more sophisticated one that we override with nonlinear. But, some architectures '#define __pa() virt_to_phys()', while others do the opposite, so that approach could be significantly more work. Does anybody really remember what the different between the __{p,v}a() functions and the virt_to_phys() ones is supposed to be? -- Dave -- 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/ . Don't email: aart@kvack.org