Hi Mahesh,
On Tue, 15 Mar 2011 10:59:24 +0530
Mahesh Jagannath Salgaonkar <mahesh at linux.vnet.ibm.com> wrote:
> >>
> >> Is there any notation in the filtered ELF kdump or compressed kdump file
> >> that filtering has been done? Given that there may be potential ramifications
> >> in crash utility behavior (or outright failure?), the crash utility should
> >> display a warning message early on during invocation.
> >
> > That is a good point.
> >
> > How about adding new members (like offset_eraseinfo, size_eraseinfo)
> > into the sub header in compressed kdump file, and setting version 5
> > in the header version (disk_dump_header.header_version) ?
> > These members show the erased information like the following:
> >
> > struct kdump_sub_header {
> > unsigned long phys_base;
> > int dump_level; /* header_version 1 and later */
> > int split; /* header_version 2 and later */
> > unsigned long start_pfn; /* header_version 2 and later */
> > unsigned long end_pfn; /* header_version 2 and later */
> > off_t offset_vmcoreinfo;/* header_version 3 and later */
> > unsigned long size_vmcoreinfo; /* header_version 3 and later */
> > off_t offset_note; /* header_version 4 and later */
> > unsigned long size_note; /* header_version 4 and later */
> > + off_t offset_eraseinfo; /* header_version 5 and later */
> > + unsigned long size_eraseinfo; /* header_version 5 and later */
> > };
> >
> > The erased information contains only effective lines in the
> > configuration file.
>
> Do you mean the info would contain symbol name/expression, resolved
> symbol/vmalloc addresses and its sizes that got filtered out?
>
> What I mean by symbol expression is, user can ask makedumpfile to erase
> a data referred by a member from the symbol variable of structure type.
> e.g.
> struct S1 {
> int a;
> };
> struct S2 {
> struct S1 *mystruct1;
> };
>
> struct S2 mystruct2;
>
> #Filter command
> erase mystruct2.mystruct1.a
>
> So the erase information in kdump header would contain:
>
> -----------------------------------
> Symbol Name: mystruct2.mystruct1.a
> Filter Addr: &mystruct2.mystruct1->a
> Filter Size: 4 (sizeof type int)
> -----------------------------------
>
> For erase commands in loop construct we will have multiple Filter addresses.
>
> Please let me know your comment on the above format.
In my idea, offset_eraseinfo points the *file offset* of the erased
information and size_eraseinfo is the information size.
The erased information would contain *multiple* erased symbol names.
For example, the following is based on your above example.
struct S1 {
int a;
int b;
int c;
};
struct S2 {
struct S1 *mystruct1;
struct S1 *mystruct2;
};
struct S2 mystruct2;
#Filter command
erase mystruct2.mystruct1.a
erase mystruct2.mystruct1.c
erase mystruct2.mystruct2.b
#The erased information
erase mystruct2.mystruct1.a 4
erase mystruct2.mystruct1.c 4
erase mystruct2.mystruct2.b 4
The dumpfile image :
header dump data the erased information
+------------------+-----------------------+-------------------------------+
| ................ | ..................... | erase mystruct2.mystruct1.a 4 |
| offset_eraseinfo | ..................... | erase mystruct2.mystruct1.c 4 |
| size_eraseinfo | ..................... | erase mystruct2.mystruct2.b 4 |
+------------------+-------------------------------------------------------+
: offset_eraseinfo (offset in dumpfile)
<------ size_eraseinfo ------->
Thanks
Ken'ichi Ohmichi
