Memory attributes triumphs over dcache

[fche at redhat dot com (Frank Ch. Eigler)]

Hi -

With the memory attribute system's arrival, the independent
remotecache (dcache) engine has apparently been shut down, as the
memory attribute system doesn't provide a usable alternative.

Many targets have plain simple RAM over the regions of interest to
gdb.  Such regions appear to be hard to describe with memory
attributes: the latter appear meant more for control registers.  For
example, memory attributes artificially force transfer chunking to
1/2/4/8 bytes.  This is a profound waste of transmit time, especially
if you make the mistake of defining the regions before downloading!
It may be sufficient to have a "width=unlimited" option available to
make it useful to cache data/insn memory.

Also, there is no automation in defining memory attributes.  It would
make sense to define memory attributes for targets based upon vital
statistics of the active executable, for example.  Contiguous
subsegments of the VMA range (.text, .data) could be added as
cacheable memory attributes fairly safely.  Somehow generically
identifying the heap & stack also would be awesome.

(Targets could also endavour to identify control register spaces or
fine-tune the generic memory regions.)


- FChE