RE: [PATCH 1/2 v4] kdump: add the vmcoreinfo documentation

[Kazuhito Hagio]

Hi Lianbo,

-----Original Message-----
> +=======================
> +What is the VMCOREINFO?
> +=======================
> +
> +VMCOREINFO is a special ELF note section. It contains various
> +information from the kernel like structure size, page size, symbol
> +values, field offsets, etc. These data are packed into an ELF note
> +section and used by user-space tools like crash and makedumpfile to
> +analyze a kernel's memory layout.
> +
> +To dump the VMCOREINFO contents, one can do:
> +
> +# makedumpfile -g VMCOREINFO -x vmlinux

again, this command does not dump the VMCOREINFO in ELF note section.
It converts the vmlinux's debug infomation into a VMCOREINFO-like data.
So I don't think this command is suitable to introduce here.

> +PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_slab|
> +PG_hwpoision|PG_head_mask
> +-----------------------------------------------------
> +
> +Page attributes. These flags are used to filter free pages.

Some of these are not used to filter *free* pages, so

... used to filter various unnecessary pages.

> +PAGE_BUDDY_MAPCOUNT_VALUE or ~PG_buddy
> +--------------------------------------

then, this can be merged into the one above?

> +======
> +x86_64
> +======
...
> +PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline)
> +----------------------------------------

This looks not only for x86_64, and also can be merged into
the PG_* flags?

Thank you for your effort!
Kazu