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x86/setup: Enhance the comments 

Update various comments, fix outright mistakes and meaningless descriptions.

Also harmonize the style across the file, both in form and in language.

Cc: linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2019-11-18 16:03:39 +01:00
parent 12609013c4
commit 360db4ace3
1 changed files with 25 additions and 16 deletions
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41
arch/x86/kernel/setup.c
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@ -43,11 +43,11 @@
#include <asm/vsyscall.h>
/*
* max_low_pfn_mapped: highest direct mapped pfn under 4GB
* max_pfn_mapped: highest direct mapped pfn over 4GB
* max_low_pfn_mapped: highest directly mapped pfn < 4 GB
* max_pfn_mapped: highest directly mapped pfn > 4 GB
*
* The direct mapping only covers E820_TYPE_RAM regions, so the ranges and gaps are
* represented by pfn_mapped
* represented by pfn_mapped[].
*/
unsigned long max_low_pfn_mapped;
unsigned long max_pfn_mapped;
@ -57,14 +57,23 @@ RESERVE_BRK(dmi_alloc, 65536);
#endif
static __initdata unsigned long _brk_start = (unsigned long)__brk_base;
unsigned long _brk_end = (unsigned long)__brk_base;
/*
* Range of the BSS area. The size of the BSS area is determined
* at link time, with RESERVE_BRK*() facility reserving additional
* chunks.
*/
static __initdata
unsigned long _brk_start = (unsigned long)__brk_base;
unsigned long _brk_end = (unsigned long)__brk_base;
struct boot_params boot_params;
/*
* Machine setup..
* These are the four main kernel memory regions, we put them into
* the resource tree so that kdump tools and other debugging tools
* recover it:
*/
static struct resource rodata_resource = {
.name = "Kernel rodata",
.start = 0,
@ -95,16 +104,16 @@ static struct resource bss_resource = {
#ifdef CONFIG_X86_32
/* cpu data as detected by the assembly code in head_32.S */
/* CPU data as detected by the assembly code in head_32.S */
struct cpuinfo_x86 new_cpu_data;
/* common cpu data for all cpus */
/* Common CPU data for all CPUs */
struct cpuinfo_x86 boot_cpu_data __read_mostly;
EXPORT_SYMBOL(boot_cpu_data);
unsigned int def_to_bigsmp;
/* for MCA, but anyone else can use it if they want */
/* For MCA, but anyone else can use it if they want */
unsigned int machine_id;
unsigned int machine_submodel_id;
unsigned int BIOS_revision;
@ -390,15 +399,15 @@ static void __init memblock_x86_reserve_range_setup_data(void)
/*
* Keep the crash kernel below this limit.
*
* On 32 bits earlier kernels would limit the kernel to the low 512 MiB
* Earlier 32-bits kernels would limit the kernel to the low 512 MB range
* due to mapping restrictions.
*
* On 64bit, kdump kernel need be restricted to be under 64TB, which is
* 64-bit kdump kernels need to be restricted to be under 64 TB, which is
* the upper limit of system RAM in 4-level paging mode. Since the kdump
* jumping could be from 5-level to 4-level, the jumping will fail if
* kernel is put above 64TB, and there's no way to detect the paging mode
* of the kernel which will be loaded for dumping during the 1st kernel
* bootup.
* jump could be from 5-level paging to 4-level paging, the jump will fail if
* the kernel is put above 64 TB, and during the 1st kernel bootup there's
* no good way to detect the paging mode of the target kernel which will be
* loaded for dumping.
*/
#ifdef CONFIG_X86_32
# define CRASH_ADDR_LOW_MAX SZ_512M
@ -809,7 +818,7 @@ void __init setup_arch(char **cmdline_p)
/*
* Note: Quark X1000 CPUs advertise PGE incorrectly and require
* a cr3 based tlb flush, so the following __flush_tlb_all()
* will not flush anything because the cpu quirk which clears
* will not flush anything because the CPU quirk which clears
* X86_FEATURE_PGE has not been invoked yet. Though due to the
* load_cr3() above the TLB has been flushed already. The
* quirk is invoked before subsequent calls to __flush_tlb_all()