Differences between revisions 37 and 39 (spanning 2 versions)
Revision 37 as of 2010-02-23 22:05:46
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Editor: TomTromey
Comment: formatting fix
Revision 39 as of 2010-06-03 17:56:15
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Comment: Set `Watchpoints on unreadable memory need no singlestepping' PR; I have not found any patch posted for it.
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 * There is a lot of duplication of linux target support in gdb and gdbserver. IWBN to consolidate this.
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 * GDB issues an error if you try to set a hardware watchpoint on an unreadable address (for instance, an address which has not been malloc'd yet). It disables watchpoints when addresses become unreadable. Hardware permitting, it would be great to be able to set watchpoints in advance. With address space randomization turned off, as it still is on many systems, this would let you restart a program and find the first write to a heap data structure. (A patch has been posted for this.)  * GDB issues an error if you try to set a hardware watchpoint on an unreadable address (for instance, an address which has not been malloc'd yet). It disables watchpoints when addresses become unreadable. Hardware permitting, it would be great to be able to set watchpoints in advance. With address space randomization turned off, as it still is on many systems, this would let you restart a program and find the first write to a heap data structure. (A patch has been posted for this, [[http://sourceware.org/bugzilla/show_bug.cgi?id=10645|PR 10645]].)

This is a list of project ideas for GDB - potential improvements, new features, et cetera. If you have a large project to add to this list, you may want to put just a brief description and a link to a new Wiki page.

Fix known bugs

  • There are lots of bugs in the bugzilla database. Everyone is welcome to look at them, reproduce them, comment on them, fix them, et cetera!

  • There are testsuite failures running 'make check' on many systems. Each one of these failures should be investigated, and either fixed or the testsuite adjusted.
  • There are many XFAIL (expected failure) and KFAIL (known failure) markers in the testsuite. Some of the XFAIL markers are for environmental problems, for instance known bugs in some compiler versions. But others of them are for bugs in GDB that no one has looked at in a long time. There should be fewer!

General

  • The run command should support pipes, i.e., set up inferior input to come from another program. This has been asked a number of times on the GDB IRC channel.

Internals

  • The GDB internals are filled with multiple ways of doing the same tasks, all subtly different. Pick a module of GDB, look at the interfaces it exports, and think about which ones should really exist.
  • Many internal functions have been deprecated but not removed. Some of the deprecated functions do not have obvious replacements; either replacements should be created or the deprecation markers removed. Others do have obvious replacements, and only await someone to update the old uses. Just search for "deprecated" or "DEPRECATED" in the sources, and you'll find lots of instances of this problem. This is a good introductory project for someone who wants to learn about the GDB internals.
  • Enable building with -Wunused. Right now, this option is not enabled because the current sources would need to be cleaned up a bit. In particular, there are probably some unused entities left, as well as some function parameters that are unused. Enabling this option would require someone motivated to fix all the warnings that it would generate. Alternatively, we could use -Wunused minus the unused parameter warnings, which would already be a nice improvement but at a more reduced cleanup cost.
  • GDB has several functions to read strings from the inferior. They should be consolidated in one function, or at most two. These are the existing string-reading functions: target_read_string, valprint.c:read_string, read_memory_string. This list is not exhaustive, perhaps there are more functions.

  • Remove global variables. A number of GDB modules use global variables, but not for any good reason. These should be removed and turned into parameters to the functions in the module. Examples include the globals in parser-defs.h and those in buildsym.h. (Not all globals are worth removing -- anything associated with the user's state in the CLI is probably a true global.)

  • There is a lot of duplication of linux target support in gdb and gdbserver. IWBN to consolidate this.

Performance

  • A full "struct symbol" is created for enumerators. If we could avoid that, it might save a lot of space. Enumerators are a large chunk of the symbol table in some programs, because they appear in header files (e.g. from glibc, from BFD).
  • Split struct objfile into two parts so that it can be reused across inferiors. The basic out line of this idea is here.

Watchpoints

  • GDB issues an error if you try to set a hardware watchpoint on an unreadable address (for instance, an address which has not been malloc'd yet). It disables watchpoints when addresses become unreadable. Hardware permitting, it would be great to be able to set watchpoints in advance. With address space randomization turned off, as it still is on many systems, this would let you restart a program and find the first write to a heap data structure. (A patch has been posted for this, PR 10645.)

  • The way the code calls watchpoints "in scope" or "out of scope" is misleading: it's not about scope, it's about what the ISO C standard calls "lifetime". For example, a static variable local to some block is only "in scope" for PC values that fall within that block, but the variable's lifetime is the execution of the entire program (or until the shared library that contains the function is dlclosed). A watchpoint should be deleted when the lifetime of any of the objects it refers to ends, regardless of whether they are in scope or not. We should change the comments and the names of any related functions, variables, fields, etc. to use "lifetime" instead of "scope".

MI (Machine Interface)

  • The current MI implementation does not follow its own quoting rules, as described in the manual. Many commands delegate to CLI commands and let the CLI support code parse options themselves. We should not change the quoting rules for MI version 2, as currently implemented, but when we switch over to MI version 3 it would be good to get these correct. That means having two code paths for each mishandled command, one which imitates the existing bad quoting behavior and one which gets it right. There's a description of the current state in the GDB mailing list archives.

Embedded Debugging

Plug-in for IDE( Integrated Development Environment )

  • integrate gdb support for MS Visual Studio
  • support local gdb provided by Cygwin or MinGW
  • support remote gdb on another machine

None: ProjectIdeas (last edited 2021-03-10 14:25:22 by TomTromey)

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