----- kexec-request at lists.infradead.org wrote:
>
> Message: 1
> Date: Mon, 26 Apr 2010 12:03:30 +0300
> From: Mika Westerberg <ext-mika.1.westerberg at nokia.com>
> To: kexec at lists.infradead.org
> Cc: linux-arm-kernel at lists.infradead.org
> Subject: [PATCH 1/2] kexec: add phys_offset field
> Message-ID:
>
> <e376969c3d29696ce11488af59605ada56fdccff.1272271391.git.ext-mika.1.westerberg at nokia.com>
>
>
> Add new field 'phys_offset' to struct elf_info. This field is used to calculate
> virtual address of PT_LOAD segment on architectures where physical memory
> doesn't always start at address 0 (namely ARM).
>
> Signed-off-by: Mika Westerberg <ext-mika.1.westerberg at nokia.com>
> ---
> kexec/crashdump-elf.c | 9 ++++++++-
> kexec/crashdump.h | 1 +
> 2 files changed, 9 insertions(+), 1 deletions(-)
>
> diff --git a/kexec/crashdump-elf.c b/kexec/crashdump-elf.c
> index 6bcef8d..1291174 100644
> --- a/kexec/crashdump-elf.c
> +++ b/kexec/crashdump-elf.c
> @@ -236,7 +236,14 @@ int FUNC(struct kexec_info *info,
> * memory region.
> */
> phdr->p_paddr = mstart;
> - phdr->p_vaddr = mstart + elf_info->page_offset;
> + /*
> + * In some architectures (namely ARM), physical memory doesn't
> + * always start at 0 so we need to calculate virtual address
> + * based on elf_info->phys_offset like:
> + * virt = phys + page_offset - phys_offset
> + */
> + phdr->p_vaddr = mstart + elf_info->page_offset -
> + elf_info->phys_offset;
> phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
> /* Do we need any alignment of segments? */
> phdr->p_align = 0;
> diff --git a/kexec/crashdump.h b/kexec/crashdump.h
> index 30d6f29..8c0ccda 100644
> --- a/kexec/crashdump.h
> +++ b/kexec/crashdump.h
> @@ -27,6 +27,7 @@ struct crash_elf_info {
> unsigned long backup_src_end;
>
> unsigned long long page_offset;
> + unsigned long long phys_offset;
> unsigned long lowmem_limit;
>
> int (*get_note_info)(int cpu, uint64_t *addr, uint64_t *len);
> --
Can you can possibly leave the p_vaddr field as-is on the other
non-ARM architectures?
The p_vaddr field in the ELF header has always been presumed
to be a kernel unity-mapped virtual address. As I understand
it, this will create a "hybrid" virtual address that is no longer
aligned with the kernel's concept of a unity-mapped address.
The crash utility for other architectures calculates the phys_offset,
or has the phys_base passed in the makedumpfile header.
Dave Anderson
