2009-11-22 10:25:58

by Yinghai Lu

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Subject: [PATCH] x86: crash kernel reserve with reserve_early



Attachments:
crashkernel_early.patch (3.07 kB)

2009-11-22 12:57:03

by Eric W. Biederman

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Subject: Re: [PATCH] x86: crash kernel reserve with reserve_early

Yinghai Lu <[email protected]> writes:

> [PATCH] x86: crash kernel reserve with reserve_early
>
> use find_e820_area/reserve_early instead.
> will get next good one automatically with alignment

Semantically this is broken, as you are now ignoring a passed in
base address if one is supplied. What problem are you trying to fix?

Eric

>
> Signed-off-by: Yinghai Lu <[email protected]>
> ---
> arch/x86/kernel/setup.c | 60 ++++++++++--------------------------------------
> 1 file changed, 13 insertions(+), 47 deletions(-)
>
> Index: linux-2.6/arch/x86/kernel/setup.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/setup.c
> +++ linux-2.6/arch/x86/kernel/setup.c
> @@ -488,42 +488,11 @@ static void __init reserve_early_setup_d
>
> #ifdef CONFIG_KEXEC
>
> -/**
> - * Reserve @size bytes of crashkernel memory at any suitable offset.
> - *
> - * @size: Size of the crashkernel memory to reserve.
> - * Returns the base address on success, and -1ULL on failure.
> - */
> -static
> -unsigned long long __init find_and_reserve_crashkernel(unsigned long long size)
> -{
> - const unsigned long long alignment = 16<<20; /* 16M */
> - unsigned long long start = 0LL;
> -
> - while (1) {
> - int ret;
> -
> - start = find_e820_area(start, ULONG_MAX, size, alignment);
> - if (start == -1ULL)
> - return start;
> -
> - /* try to reserve it */
> - ret = reserve_bootmem_generic(start, size, BOOTMEM_EXCLUSIVE);
> - if (ret >= 0)
> - return start;
> -
> - start += alignment;
> - }
> -}
> -
> static inline unsigned long long get_total_mem(void)
> {
> unsigned long long total;
>
> - total = max_low_pfn - min_low_pfn;
> -#ifdef CONFIG_HIGHMEM
> - total += highend_pfn - highstart_pfn;
> -#endif
> + total = max_pfn - min_low_pfn;
>
> return total << PAGE_SHIFT;
> }
> @@ -532,6 +501,8 @@ static void __init reserve_crashkernel(v
> {
> unsigned long long total_mem;
> unsigned long long crash_size, crash_base;
> + const unsigned long long alignment = 16<<20; /* 16M */
> + unsigned long long start;
> int ret;
>
> total_mem = get_total_mem();
> @@ -543,21 +514,16 @@ static void __init reserve_crashkernel(v
>
> /* 0 means: find the address automatically */
> if (crash_base <= 0) {
> - crash_base = find_and_reserve_crashkernel(crash_size);
> - if (crash_base == -1ULL) {
> - pr_info("crashkernel reservation failed. "
> - "No suitable area found.\n");
> - return;
> - }
> + start = alignment;
> } else {
> - ret = reserve_bootmem_generic(crash_base, crash_size,
> - BOOTMEM_EXCLUSIVE);
> - if (ret < 0) {
> - pr_info("crashkernel reservation failed - "
> - "memory is in use\n");
> - return;
> - }
> + start = crash_base;
> + }
> + crash_base = find_e820_area(start, ULONG_MAX, crash_size, alignment);
> + if (crash_base == -1ULL) {
> + pr_info("crashkernel reservation failed - No suitable area found.\n");
> + return;
> }
> + reserve_early(crash_base, crash_base + crash_size, "CRASH KERNEL");
>
> printk(KERN_INFO "Reserving %ldMB of memory at %ldMB "
> "for crashkernel (System RAM: %ldMB)\n",
> @@ -935,6 +901,8 @@ void __init setup_arch(char **cmdline_p)
>
> reserve_initrd();
>
> + reserve_crashkernel();
> +
> vsmp_init();
>
> io_delay_init();
> @@ -965,8 +933,6 @@ void __init setup_arch(char **cmdline_p)
>
> initmem_init(0, max_pfn, acpi, k8);
>
> - reserve_crashkernel();
> -
> #ifdef CONFIG_X86_64
> /*
> * dma32_reserve_bootmem() allocates bootmem which may conflict

2009-11-23 01:18:07

by Yinghai Lu

[permalink] [raw]
Subject: Re: [PATCH] x86: crash kernel reserve with reserve_early

On Sun, Nov 22, 2009 at 4:56 AM, Eric W. Biederman
<[email protected]> wrote:
> Yinghai Lu <[email protected]> writes:
>
>> [PATCH] x86: crash kernel reserve with reserve_early
>>
>> use find_e820_area/reserve_early instead.
>> will get next good one automatically with alignment
>
> Semantically this is broken, as you are now ignoring a passed in
> base address if one is supplied. ?What problem are you trying to fix?

avoid to use bootmem.

also simpify the code.

YH