mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-13 07:08:21 -04:00
per cpu data section contains two types of data. One set which is exclusively accessed by the local cpu and the other set which is per cpu, but also shared by remote cpus. In the current kernel, these two sets are not clearely separated out. This can potentially cause the same data cacheline shared between the two sets of data, which will result in unnecessary bouncing of the cacheline between cpus. One way to fix the problem is to cacheline align the remotely accessed per cpu data, both at the beginning and at the end. Because of the padding at both ends, this will likely cause some memory wastage and also the interface to achieve this is not clean. This patch: Moves the remotely accessed per cpu data (which is currently marked as ____cacheline_aligned_in_smp) into a different section, where all the data elements are cacheline aligned. And as such, this differentiates the local only data and remotely accessed data cleanly. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Christoph Lameter <clameter@sgi.com> Cc: <linux-arch@vger.kernel.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
214 lines
5.3 KiB
ArmAsm
214 lines
5.3 KiB
ArmAsm
/* ld script to make i386 Linux kernel
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* Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>;
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*
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* Don't define absolute symbols until and unless you know that symbol
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* value is should remain constant even if kernel image is relocated
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* at run time. Absolute symbols are not relocated. If symbol value should
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* change if kernel is relocated, make the symbol section relative and
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* put it inside the section definition.
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*/
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/* Don't define absolute symbols until and unless you know that symbol
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* value is should remain constant even if kernel image is relocated
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* at run time. Absolute symbols are not relocated. If symbol value should
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* change if kernel is relocated, make the symbol section relative and
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* put it inside the section definition.
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*/
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#define LOAD_OFFSET __PAGE_OFFSET
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#include <asm-generic/vmlinux.lds.h>
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#include <asm/thread_info.h>
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#include <asm/page.h>
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#include <asm/cache.h>
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#include <asm/boot.h>
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OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
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OUTPUT_ARCH(i386)
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ENTRY(phys_startup_32)
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jiffies = jiffies_64;
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PHDRS {
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text PT_LOAD FLAGS(5); /* R_E */
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data PT_LOAD FLAGS(7); /* RWE */
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note PT_NOTE FLAGS(0); /* ___ */
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}
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SECTIONS
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{
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. = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;
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phys_startup_32 = startup_32 - LOAD_OFFSET;
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.text.head : AT(ADDR(.text.head) - LOAD_OFFSET) {
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_text = .; /* Text and read-only data */
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*(.text.head)
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} :text = 0x9090
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/* read-only */
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.text : AT(ADDR(.text) - LOAD_OFFSET) {
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TEXT_TEXT
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SCHED_TEXT
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LOCK_TEXT
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KPROBES_TEXT
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*(.fixup)
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*(.gnu.warning)
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_etext = .; /* End of text section */
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} :text = 0x9090
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. = ALIGN(16); /* Exception table */
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__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
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__start___ex_table = .;
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*(__ex_table)
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__stop___ex_table = .;
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}
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BUG_TABLE
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. = ALIGN(4);
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.tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {
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__tracedata_start = .;
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*(.tracedata)
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__tracedata_end = .;
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}
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RODATA
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/* writeable */
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. = ALIGN(4096);
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.data : AT(ADDR(.data) - LOAD_OFFSET) { /* Data */
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DATA_DATA
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CONSTRUCTORS
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} :data
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. = ALIGN(4096);
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.data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
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__nosave_begin = .;
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*(.data.nosave)
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. = ALIGN(4096);
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__nosave_end = .;
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}
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. = ALIGN(4096);
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.data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) {
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*(.data.page_aligned)
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*(.data.idt)
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}
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. = ALIGN(32);
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.data.cacheline_aligned : AT(ADDR(.data.cacheline_aligned) - LOAD_OFFSET) {
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*(.data.cacheline_aligned)
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}
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/* rarely changed data like cpu maps */
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. = ALIGN(32);
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.data.read_mostly : AT(ADDR(.data.read_mostly) - LOAD_OFFSET) {
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*(.data.read_mostly)
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_edata = .; /* End of data section */
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}
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. = ALIGN(THREAD_SIZE); /* init_task */
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.data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) {
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*(.data.init_task)
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}
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/* might get freed after init */
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. = ALIGN(4096);
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.smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
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__smp_locks = .;
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*(.smp_locks)
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__smp_locks_end = .;
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}
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/* will be freed after init
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* Following ALIGN() is required to make sure no other data falls on the
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* same page where __smp_alt_end is pointing as that page might be freed
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* after boot. Always make sure that ALIGN() directive is present after
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* the section which contains __smp_alt_end.
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*/
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. = ALIGN(4096);
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/* will be freed after init */
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. = ALIGN(4096); /* Init code and data */
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.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
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__init_begin = .;
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_sinittext = .;
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*(.init.text)
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_einittext = .;
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}
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.init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { *(.init.data) }
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. = ALIGN(16);
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.init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) {
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__setup_start = .;
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*(.init.setup)
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__setup_end = .;
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}
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.initcall.init : AT(ADDR(.initcall.init) - LOAD_OFFSET) {
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__initcall_start = .;
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INITCALLS
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__initcall_end = .;
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}
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.con_initcall.init : AT(ADDR(.con_initcall.init) - LOAD_OFFSET) {
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__con_initcall_start = .;
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*(.con_initcall.init)
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__con_initcall_end = .;
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}
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SECURITY_INIT
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. = ALIGN(4);
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.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
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__alt_instructions = .;
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*(.altinstructions)
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__alt_instructions_end = .;
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}
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.altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
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*(.altinstr_replacement)
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}
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. = ALIGN(4);
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.parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
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__parainstructions = .;
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*(.parainstructions)
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__parainstructions_end = .;
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}
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/* .exit.text is discard at runtime, not link time, to deal with references
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from .altinstructions and .eh_frame */
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.exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) { *(.exit.text) }
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.exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) { *(.exit.data) }
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#if defined(CONFIG_BLK_DEV_INITRD)
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. = ALIGN(4096);
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.init.ramfs : AT(ADDR(.init.ramfs) - LOAD_OFFSET) {
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__initramfs_start = .;
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*(.init.ramfs)
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__initramfs_end = .;
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}
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#endif
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. = ALIGN(4096);
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.data.percpu : AT(ADDR(.data.percpu) - LOAD_OFFSET) {
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__per_cpu_start = .;
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*(.data.percpu)
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*(.data.percpu.shared_aligned)
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__per_cpu_end = .;
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}
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. = ALIGN(4096);
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/* freed after init ends here */
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.bss : AT(ADDR(.bss) - LOAD_OFFSET) {
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__init_end = .;
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__bss_start = .; /* BSS */
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*(.bss.page_aligned)
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*(.bss)
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. = ALIGN(4);
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__bss_stop = .;
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_end = . ;
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/* This is where the kernel creates the early boot page tables */
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. = ALIGN(4096);
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pg0 = . ;
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}
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/* Sections to be discarded */
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/DISCARD/ : {
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*(.exitcall.exit)
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}
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STABS_DEBUG
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DWARF_DEBUG
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NOTES
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}
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