If you find inaccuracies in this list, please send mail to
-bug-gdb@prep.ai.mit.edu. If you would like to work on any of these,
-you should consider sending mail to the same address, to find out
-whether anyone else is working on it.
+gdb-patches@sourceware.cygnus.com. If you would like to work on any
+of these, you should consider sending mail to the same address, to
+find out whether anyone else is working on it.
-Known problems in GDB 5.0
-=========================
+ Known problems in GDB 5.0
+ =========================
Below is a list of problems identified during the GDB 5.0 release
cycle. People hope to have these problems fixed in a follow-on
--
- ------------------------------------------------
-
-Code cleanups
-=============
+ Code cleanups
+ =============
The following code cleanups are planned for the follow-on release to
GDB 5.0.
--
-General Wish List
-=================
+ General Wish List
+ =================
+
+--
+
+Register Cache Cleanup (below from Andrew Cagney)
+
+I would depict the current register architecture as something like:
+
+ High GDB --> Low GDB
+ | |
+ \|/ \|/
+ --- REG NR -----
+ |
+ register + REGISTER_BYTE(reg_nr)
+ |
+ \|/
+ -------------------------
+ | extern register[] |
+ -------------------------
+
+where neither the high (valops.c et.al.) or low gdb (*-tdep.c) are
+really clear on what mechanisms they should be using to manipulate that
+buffer. Further, much code assumes, dangerously, that registers are
+contigious. Having got mips-tdep.c to support multiple ABIs, believe
+me, that is a bad assumption. Finally, that register cache layout is
+determined by the current remote/local target and _not_ the less
+specific target ISA. In fact, in many cases it is determined by the
+somewhat arbitrary layout of the [gG] packets!
+
+
+How I would like the register file to work is more like:
+
+
+ High GDB
+ |
+ \|/
+ pseudo reg-nr
+ |
+ map pseudo <->
+ random cache
+ bytes
+ |
+ \|/
+ ------------
+ | register |
+ | cache |
+ ------------
+ /|\
+ |
+ map random cache
+ bytes to target
+ dependant i-face
+ /|\
+ |
+ target dependant
+ such as [gG] packet
+ or ptrace buffer
+
+The main objectives being:
+
+ o a clear separation between the low
+ level target and the high level GDB
+
+ o a mechanism that solves the general
+ problem of register aliases, overlaps
+ etc instead of treating them as optional
+ extras that can be wedged in as an after
+ thought (that is a reasonable description
+ of the current code).
+
+ Identify then solve the hard case and the
+ rest just falls out. GDB solved the easy
+ case and then tried to ignore the real
+ world :-)
+
+ o a removal of the assumption that the
+ mapping between the register cache
+ and virtual registers is largely static.
+ If you flip the USR/SSR stack register
+ select bit in the status-register then
+ the corresponding stack registers should
+ reflect the change.
+
+ o a mechanism that clearly separates the
+ gdb internal register cache from any
+ target (not architecture) dependant
+ specifics such as [gG] packets.
+
+Of course, like anything, it sounds good in theory. In reality, it
+would have to contend with many<->many relationships at both the
+virt<->cache and cache<->target level. For instance:
+
+ virt<->cache
+ Modifying an mmx register may involve
+ scattering values across both FP and
+ mmpx specific parts of a buffer
+
+ cache<->target
+ When writing back a SP it may need to
+ both be written to both SP and USP.
+
+
+Hmm,
+
+Rather than let this like the last time it was discussed, just slip, I'm
+first going to add this e-mail (+ references) to TODO. I'd then like to
+sketch out a broad strategy I think could get us there.
+
+
+First thing I'd suggest is separating out the ``extern registers[]''
+code so that we can at least identify what is using it. At present
+things are scattered across many files. That way we can at least
+pretend that there is a cache instead of a global array :-)
+
+I'd then suggest someone putting up a proposal for the pseudo-reg /
+high-level side interface so that code can be adopted to it. For old
+code, initially a blanket rename of write_register_bytes() to
+deprecated_write_register_bytes() would help.
+
+Following that would, finaly be the corresponding changes to the target.
--
--
-This list is probably not up to date, and opinions vary about the
-importance or even desirability of some of the items.
+Add support for Modula3
+
+Get DEC/Compaq to contribute their Modula-3 support.
+
+--
+
+ Legacy Wish List
+ ================
+
+This list is not up to date, and opinions vary about the importance or
+even desirability of some of the items. If you do fix something, it
+always pays to check the below.
+
+--
Document trace machinery.
projects / deliverable / binutils-gdb.git / commitdiff
