Re: [Crash-utility] [PATCH] add -s option for struct command
----- Original Message -----
Hello Dave,
The patch attached with this mail is to add "-s" option for struct
command. The output is like below.
crash> page.private,_mapcount.counter,lru.next -s ffffea0000000850
0 -1 0xffffea0000000878
crash> page.private,_mapcount.counter,lru.next -s ffffea0000000850 -h
0x0 0xffffffff 0xffffea0000000878
There are three features provided by the patches.
1. the data can be output in one line, easier to be parsed
2. it is extremly faster than original struct command and print command.
When using command like "struct xxx.yyy -s < address_list", if there are
lots of addresses in the file, address_list, the original struct command
will spend several minutes and even several hours. But the patch will
reduce the time to several seconds.
3. submember can also be output, like "_mapcount.counter" int the above
example
P.S.
The first patch is used to modified gdb. It add a command called
"printm", which can output the relative information of a struct's
member.
In our original discussions, i thought that I had made it clear that
the introduction of a new option paradigm with submembers could be
avoided by using, for example, "page._mapcounter" instead of having
to enter "page._mapcount.counter"? This option makes the struct
command seemingly violate its own rules, and really confuses things.
For example, with your patch, a user would see things like this:
crash> page._mapcount.counter ffffea0000000508 -s
-1
crash> page._mapcount.counter ffffea0000000508
struct: invalid format: page._mapcount.counter
crash> page._mapcount ffffea0000000508
_mapcount = {
counter = -1
}
crash> page._mapcount ffffea0000000508 -s
struct: invalid data structure reference page._mapcount
crash>
I had suggested that you look into the get_member_data() function
in to the gdb/symtab.c file to access the member offset and size
values.
I also don't like the idea of modifying the prototype of
the stalwart print_command_1() gdb function, and the creation
of a new gdb command. Whenever there is a need to update the
embedded gdb version, patches like this can be problematic.
I would prefer that you create a new "GNU_XXXX" #define,
similar to GNU_GET_SYMBOL_TYPE, pass the request through
the gdb_command_funnel switch statement, and write a new
standalone function to accomplish what you have done in the
print_command_1() function.
Dave