[PATCH v6 9/9] x86: Pass memory range via E820 for kdump

[Dave Young]

On 04/14/14 at 10:55pm, 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>
> ---
>  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 7b618a6..4a1491b 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, 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 + 1;
>  		add_memmap(memmap_p, &nr_memmap, 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);

Seems memmap_p contains the acpi ranges as well, so cmdline_add_memmap_acpi is
not necessary anymore, just improve cmdline_add_memmap to add both RAM and ACPI
ranges is enough.

Thanks
Dave