[PATCH] kexec: extend for large cpu count and memory

[Simon Horman]

Hi Cliff,

On Tue, Jun 15, 2010 at 02:49:19PM -0500, Cliff Wickman wrote:
> 
> The MAX_MEMORY_RANGES of 64 is too small for a very large NUMA machine.
> (A 512 processor SGI UV, for example.)
>  Gentlemen,
>   You may judge increasing MAX_MEMORY_RANGES to 1024 may be excessive
>   and I will not argue against setting it to maybe half of that.  But a large
>   number is the easy cure, in lieu of sizing memory_range[] and
>   crash_memory_range[] dynamically.

Agreed.

> And fix a temporary workaround (hack) in load_crashdump_segments() that
> assumes that 16k is sufficient for the size of the crashdump elf header.
> This is too small for a machine with a large cpu count. A PT_NOTE is created
> in the elf header for each cpu.
> 
> And the below fiddling with temp_region is just to prevent compiler warnings.
> 
> Diffed against kexec-tools-2.0.1

Could you provide a diff against the current git tree?
In particular, I think that the temp_region fiddling has already been done.

http://git.kernel.org/?p=linux/kernel/git/horms/kexec-tools.git;a=summary

> Signed-off-by: Cliff Wickman <cpw at sgi.com>
> 
> ---
>  kexec/arch/i386/kexec-x86.h          |    2 +-
>  kexec/arch/x86_64/crashdump-x86_64.c |   19 +++++++++++++++----
>  2 files changed, 16 insertions(+), 5 deletions(-)
> 
> Index: kexec-tools-2.0.1/kexec/arch/i386/kexec-x86.h
> ===================================================================
> --- kexec-tools-2.0.1.orig/kexec/arch/i386/kexec-x86.h
> +++ kexec-tools-2.0.1/kexec/arch/i386/kexec-x86.h
> @@ -1,7 +1,7 @@
>  #ifndef KEXEC_X86_H
>  #define KEXEC_X86_H
>  
> -#define MAX_MEMORY_RANGES 64
> +#define MAX_MEMORY_RANGES 1024
>  
>  enum coretype {
>  	CORE_TYPE_UNDEF = 0,
> Index: kexec-tools-2.0.1/kexec/arch/x86_64/crashdump-x86_64.c
> ===================================================================
> --- kexec-tools-2.0.1.orig/kexec/arch/x86_64/crashdump-x86_64.c
> +++ kexec-tools-2.0.1/kexec/arch/x86_64/crashdump-x86_64.c
> @@ -268,6 +268,9 @@ static int exclude_region(int *nr_ranges
>  {
>  	int i, j, tidx = -1;
>  	struct memory_range temp_region;
> +	temp_region.start = 0;
> +	temp_region.end = 0;
> +	temp_region.type = 0;
>  
>  	for (i = 0; i < (*nr_ranges); i++) {
>  		unsigned long long mstart, mend;
> @@ -403,6 +406,7 @@ static int delete_memmap(struct memory_r
>  				memmap_p[i].end = addr - 1;
>  				temp_region.start = addr + size;
>  				temp_region.end = mend;
> +				temp_region.type = memmap_p[i].type;
>  				operation = 1;
>  				tidx = i;
>  				break;
> @@ -580,7 +584,7 @@ int load_crashdump_segments(struct kexec
>  				unsigned long max_addr, unsigned long min_base)
>  {
>  	void *tmp;
> -	unsigned long sz, elfcorehdr;
> +	unsigned long sz, bufsz, memsz, elfcorehdr;
>  	int nr_ranges, align = 1024, i;
>  	struct memory_range *mem_range, *memmap_p;
>  
> @@ -613,9 +617,10 @@ int load_crashdump_segments(struct kexec
>  	/* Create elf header segment and store crash image data. */
>  	if (crash_create_elf64_headers(info, &elf_info,
>  				       crash_memory_range, nr_ranges,
> -				       &tmp, &sz,
> +				       &tmp, &bufsz,
>  				       ELF_CORE_HEADER_ALIGN) < 0)
>  		return -1;
> +	/* the size of the elf headers allocated is returned in 'bufsz' */
>  
>  	/* Hack: With some ld versions (GNU ld version 2.14.90.0.4 20030523),
>  	 * vmlinux program headers show a gap of two pages between bss segment
> @@ -624,9 +629,15 @@ int load_crashdump_segments(struct kexec
>  	 * elf core header segment to 16K to avoid being placed in such gaps.
>  	 * This is a makeshift solution until it is fixed in kernel.
>  	 */
> -	elfcorehdr = add_buffer(info, tmp, sz, 16*1024, align, min_base,
> +	if (bufsz < (16*1024))
> +		/* bufsize is big enough for all the PT_NOTE's and PT_LOAD's */
> +		memsz = 16*1024;
> +		/* memsz will be the size of the memory hole we look for */
> +	else
> +		memsz = bufsz;

I'm unsure of the reasoning between using 16*1024 at all?
Can we just always use memsz = bufsz?

> +	elfcorehdr = add_buffer(info, tmp, bufsz, memsz, align, min_base,
>  							max_addr, -1);
> -	if (delete_memmap(memmap_p, elfcorehdr, sz) < 0)
> +	if (delete_memmap(memmap_p, elfcorehdr, memsz) < 0)
>  		return -1;
>  	cmdline_add_memmap(mod_cmdline, memmap_p);
>  	cmdline_add_elfcorehdr(mod_cmdline, elfcorehdr);
> 
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