[PATCH v5 09/10] x86: Pass memory range via E820 for kdump

[Dave Young]

On 04/10/14 at 05:13pm, WANG Chao wrote:
> command line size is restricted by kernel, sometimes memmap=exactmap has
> too many memory ranges to pass to cmdline. And also memmap=exactmap and
> kASLR doesn't work together.
> 
> A better approach, to pass the memory ranges for crash kernel to boot
> into, is filling the memory ranges into E820.
> 
> boot_params only got 128 slots for E820 map to fit in, when the number of
> memory map exceeds 128, use setup_data to pass the rest as extended E820
> memory map.
> 
> kexec boot could also benefit from setup_data in case E820 memory map
> exceeds 128.
> 
> Now this new approach becomes default instead of memmap=exactmap.
> saved_max_pfn users can specify --pass-memmap-cmdline to use the
> exactmap approach.
> 
> Signed-off-by: WANG Chao <chaowang at redhat.com>
> Tested-by: Linn Crosetto <linn at hp.com>
> Reviewed-by: Linn Crosetto <linn at hp.com>
> Signed-off-by: WANG Chao <chaowang at redhat.com>
> ---
>  kexec/arch/i386/crashdump-x86.c   |   6 +-
>  kexec/arch/i386/x86-linux-setup.c | 149 +++++++++++++++++++++++++-------------
>  kexec/arch/i386/x86-linux-setup.h |   1 +
>  3 files changed, 103 insertions(+), 53 deletions(-)
> 
> diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
> index 2a6871d..2c0dbe3 100644
> --- a/kexec/arch/i386/crashdump-x86.c
> +++ b/kexec/arch/i386/crashdump-x86.c
> @@ -979,7 +979,8 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
>  	dbgprintf("Created elf header segment at 0x%lx\n", elfcorehdr);
>  	if (delete_memmap(memmap_p, &nr_memmap_p, elfcorehdr, memsz) < 0)
>  		return -1;
> -	cmdline_add_memmap(mod_cmdline, memmap_p);
> +	if (arch_options.pass_memmap_cmdline)
> +		cmdline_add_memmap(mod_cmdline, memmap_p);
>  	if (!bzImage_support_efi_boot)
>  		cmdline_add_efi(mod_cmdline);
>  	cmdline_add_elfcorehdr(mod_cmdline, elfcorehdr);
> @@ -995,7 +996,8 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
>  		type = mem_range[i].type;
>  		size = end - start;
>  		add_memmap(memmap_p, &nr_memmap_p, start, size, type);
> -		cmdline_add_memmap_acpi(mod_cmdline, start, end);
> +		if (arch_options.pass_memmap_cmdline)
> +			cmdline_add_memmap_acpi(mod_cmdline, start, end);
>  	}
>  
>  	/* Store 2nd kernel boot memory ranges for later reference in
> diff --git a/kexec/arch/i386/x86-linux-setup.c b/kexec/arch/i386/x86-linux-setup.c
> index 8ed36cc..2f9bb97 100644
> --- a/kexec/arch/i386/x86-linux-setup.c
> +++ b/kexec/arch/i386/x86-linux-setup.c
> @@ -36,8 +36,6 @@
>  #include "x86-linux-setup.h"
>  #include "../../kexec/kexec-syscall.h"
>  
> -#define SETUP_EFI	4
> -
>  void init_linux_parameters(struct x86_linux_param_header *real_mode)
>  {
>  	/* Fill in the values that are usually provided by the kernel. */
> @@ -502,6 +500,11 @@ struct efi_setup_data {
>  struct setup_data {
>  	uint64_t next;
>  	uint32_t type;
> +#define SETUP_NONE	0
> +#define SETUP_E820_EXT	1
> +#define SETUP_DTB	2
> +#define SETUP_PCI	3
> +#define SETUP_EFI	4
>  	uint32_t len;
>  	uint8_t data[0];
>  } __attribute__((packed));
> @@ -684,6 +687,98 @@ out:
>  	return ret;
>  }
>  
> +static void add_e820_map_from_mr(struct x86_linux_param_header *real_mode,
> +			struct e820entry *e820, struct memory_range *range, int nr_range)
> +{
> +	int i;
> +
> +	for (i = 0; i < nr_range; i++) {
> +		e820[i].addr = range[i].start;
> +		e820[i].size = range[i].end - range[i].start;

I see it's same as original code but I still feel it should be end - start + 1;

Thanks
Dave