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SubjectRe: [RFC PATCH 7/8] ARM: vmlinux.lds: Setup physical load address not virtual
On Mon, 18 Jun 2012, Michal Simek wrote:

> Setup correct virtual and physical address in ELF LOAD section.

We are moving to a single kernel binary for multiple targets, including
targets with different physical load addresses. The kernel code figures
out at run time what the actual physical address is when
CONFIG_ARM_PATCH_PHYS_VIRT is set which is the default these days. In
other words, we don't know the physical offset at build time in that
case and CONFIG_PHYS_OFFSET is simply not defined.

Why do you need this change? Your patch comments are lacking
justification for them.


> Signed-off-by: Michal Simek <monstr@monstr.eu>
> ---
> arch/arm/include/asm/page.h | 2 ++
> arch/arm/kernel/vmlinux.lds.S | 28 ++++++++++++++--------------
> 2 files changed, 16 insertions(+), 14 deletions(-)
>
> diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
> index ecf9019..4070209 100644
> --- a/arch/arm/include/asm/page.h
> +++ b/arch/arm/include/asm/page.h
> @@ -15,6 +15,8 @@
> #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
> #define PAGE_MASK (~(PAGE_SIZE-1))
>
> +#define LOAD_OFFSET (CONFIG_PAGE_OFFSET - CONFIG_PHYS_OFFSET)
> +
> #ifndef __ASSEMBLY__
>
> #ifndef CONFIG_MMU
> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
> index c887be0..b996bc0 100644
> --- a/arch/arm/kernel/vmlinux.lds.S
> +++ b/arch/arm/kernel/vmlinux.lds.S
> @@ -3,11 +3,11 @@
> * Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
> */
>
> +#include <asm/page.h>
> #include <asm-generic/vmlinux.lds.h>
> #include <asm/cache.h>
> #include <asm/thread_info.h>
> #include <asm/memory.h>
> -#include <asm/page.h>
>
> #define PROC_INFO \
> . = ALIGN(4); \
> @@ -86,11 +86,11 @@ SECTIONS
> #else
> . = PAGE_OFFSET + TEXT_OFFSET;
> #endif
> - .head.text : {
> + .head.text : AT(ADDR(.head.text) - LOAD_OFFSET) {
> _text = .;
> HEAD_TEXT
> }
> - .text : { /* Real text segment */
> + .text : AT(ADDR(.text) - LOAD_OFFSET){ /* Real text segment */
> _stext = .; /* Text and read-only data */
> __exception_text_start = .;
> *(.exception.text)
> @@ -132,12 +132,12 @@ SECTIONS
> * Stack unwinding tables
> */
> . = ALIGN(8);
> - .ARM.unwind_idx : {
> + .ARM.unwind_idx : AT(ADDR(.ARM.unwind_idx) - LOAD_OFFSET) {
> __start_unwind_idx = .;
> *(.ARM.exidx*)
> __stop_unwind_idx = .;
> }
> - .ARM.unwind_tab : {
> + .ARM.unwind_tab : AT(ADDR(.ARM.unwind_tab) - LOAD_OFFSET) {
> __start_unwind_tab = .;
> *(.ARM.extab*)
> __stop_unwind_tab = .;
> @@ -152,35 +152,35 @@ SECTIONS
> #endif
>
> INIT_TEXT_SECTION(8)
> - .exit.text : {
> + .exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
> ARM_EXIT_KEEP(EXIT_TEXT)
> }
> - .init.proc.info : {
> + .init.proc.info : AT(ADDR(.init.proc.info) - LOAD_OFFSET) {
> ARM_CPU_DISCARD(PROC_INFO)
> }
> - .init.arch.info : {
> + .init.arch.info : AT(ADDR(.init.arch.info) - LOAD_OFFSET) {
> __arch_info_begin = .;
> *(.arch.info.init)
> __arch_info_end = .;
> }
> - .init.tagtable : {
> + .init.tagtable : AT(ADDR(.init.tagtable) - LOAD_OFFSET) {
> __tagtable_begin = .;
> *(.taglist.init)
> __tagtable_end = .;
> }
> #ifdef CONFIG_SMP_ON_UP
> - .init.smpalt : {
> + .init.smpalt : AT(ADDR(.init.smpalt) - LOAD_OFFSET) {
> __smpalt_begin = .;
> *(.alt.smp.init)
> __smpalt_end = .;
> }
> #endif
> - .init.pv_table : {
> + .init.pv_table : AT(ADDR(.init.pv_table) - LOAD_OFFSET) {
> __pv_table_begin = .;
> *(.pv_table)
> __pv_table_end = .;
> }
> - .init.data : {
> + .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) {
> #ifndef CONFIG_XIP_KERNEL
> INIT_DATA
> #endif
> @@ -191,7 +191,7 @@ SECTIONS
> INIT_RAM_FS
> }
> #ifndef CONFIG_XIP_KERNEL
> - .exit.data : {
> + .exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) {
> ARM_EXIT_KEEP(EXIT_DATA)
> }
> #endif
> @@ -207,7 +207,7 @@ SECTIONS
> __data_loc = .;
> #endif
>
> - .data : AT(__data_loc) {
> + .data : AT(ADDR(.data) - LOAD_OFFSET) {
> _data = .; /* address in memory */
> _sdata = .;
>
> --
> 1.7.0.4
>


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