Re: [PATCH 0/3] remove-symbol-file

[Pedro Alves <palves@redhat.com>]

On 04/25/2013 09:38 AM, Blanc, Nicolas wrote:
> 
> 
>>> session. In this context I think the text address is the most appropriate way to remove a file because:
>>>   1) the user knows exactly where the .text section was loaded,
>>
>> So how do you handle the case of there being no .text section at all?
> 
> It's a requirement of the add-symbol-file command [1]. The existing implementation of add-symbol-file assumes
> that the *mandatory* load-address argument (terminology from GDB's manual) is the address of the text section.
> See the implementation of add-symbol-file:
> 
> 	if (argcnt == 1)
> 	  {
> 	    /* The second argument is always the text address at which
>                to load the program.  */
> 	    sect_opts[section_index].name = ".text";
> 
> The second argument is not optional. The add-symbol-file command returns an error if no address is specified.

As I mentioned before, in the add case, you can just pass in a
random ADDR, I think gdb copes:

(gdb) add-symbol-file ~/data.o 0x111 -s .data 0x2000
add symbol table from file "/home/pedro/data.o" at
        .text_addr = 0x111
        .data_addr = 0x2000
(y or n) y
Reading symbols from /home/pedro/data.o...warning: section .text not found in /home/pedro/data.o

>>> Note that currently in Option 4 below ADDR is in fact 
>>> "objf->addr_low", but the command could be more generous by searching 
>>> first which file corresponds to ADDR and then removing it. This would be more flexible and an alternative to Option 3, for instance.
>> You lost me here.
> 
> It's an idea that you and Tom gave me. Given an arbitrary address, remove-symbol-file could figure out the file that
> corresponds to this address and remove it. This could make the command more flexible.

Hmm, how is that different from what the command is currently
doing?  /me looks

> But thinking twice I think that the current
> implementation of remove-symbol-file does the right thing by identifying the file to remove using the address from the
> add-symbol-file command. The user knows what address he passed to add-symbol-file.

Ah, so the current implementation stores the ADDR the user specified
with add-symbol-file.  Why didn't you say so?  ;-)

Okay, I guess that's good enough.  We can add support for "-s" too
to remove- if ever necessary.

>>> 1) remove-symbol-file FILE
>>> 2) remove-symbol-file FILE ADDR
>>> 3) remove-symbol-file -s .data DATA_ADDR
>>> 4) remove-symbol-file ADDR

-- 
Pedro Alves