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Re: [patch/rfc] target read/write partial
On Wed, Oct 15, 2003 at 06:16:28PM -0400, Andrew Cagney wrote:
Hello,
This patch adds target read/write partial methods.
It's almost ready for prime time. I want to first see through some
other target cleanups namely:
+ /* FIXME: cagney/2003-10-15: This code should walk down the target
+ stack looking for a stratum that supports the mechanism.
+ Unfortunatly, there isn't a per-target-stack chain to walk round.
+ Catch-22. */
and a s/target_ops/target/ transformation.
Preferably not target - didn't someone suggest gdbtarg? Or maybe
gdb_target.
... you mean someone actually likes gdbtarg :-)
Note that it includes:
+ /* Transfer up-to LEN bytes of memory starting at OFFSET. */
+ TARGET_OBJECT_MEMORY
I'm going to need that when implementing a per-target
CONVERT_FROM_FUNC_PTR_ADDR.
How is that different from a memory read, which we've already got? I am
guessing that it's because you want to support partial memory
operations (avoid packet size limits), but you never explained your
goal.
I previously wrote:
In the light of Joel's "upload/download" commands, and lessons (gdb/589) learn't from similar interfaces, and a realization that I need this for memory:
...
- it takes an explicit target vector
- there are both read and write variants (instead of query)
- it, what the heck, takes a LONGEST
- it makes the fact that the method isn't expected to perform a full transfer explicit
gdb/589 is yet another example of how the existing code always did
partial xfers, yet no one noticed. Have a look at how many levels of
GDB code try to locally solve the partial transfer problem when
generic_load is called.
The only significant difference is the addition of an explicit target
vector. But that's really significant. I should probably comment out
TARGET_OBJECT_MEMORY until a target implements it.
+ /* Map pre-existing objects onto letters. DO NOT do this for new
+ objects!!! Instead specify new query packets. */
Could that be a little clearer - I had to read the code a couple of
times to figure out what you meant. I guess you just want to say that
there's no need to use single letters?
The code abuses:
<letter> + <annex>
as a way of generating packets. The entire qK* and qR* packet maps have
been kidnapped by this. The un-approved RedBoot patches did the same
with qM*.
I'll expand the comment.
+ /* Minimum outbuf size is (rs->remote_packet_size) - if bufsiz is
+ not large enough let the caller. */
Missing a word there I think.
Will fix.
Andrew