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Re: [rfc/rfa] [3/4] SPU enhancements: gdbserver support
- From: Daniel Jacobowitz <drow at false dot org>
- To: Ulrich Weigand <uweigand at de dot ibm dot com>
- Cc: gdb-patches at sourceware dot org, eliz at gnu dot org
- Date: Mon, 4 Jun 2007 15:53:49 -0400
- Subject: Re: [rfc/rfa] [3/4] SPU enhancements: gdbserver support
- References: <200706021933.l52JXTJX005551@d12av02.megacenter.de.ibm.com>
On Sat, Jun 02, 2007 at 09:33:29PM +0200, Ulrich Weigand wrote:
> this patch, implemented by Markus Deuling, extends TARGET_OBJECT_SPU
> support to remote gdbserver debugging.
> This is done by extended the remote protocol by two new packet types,
> qXfer:spu:read and qXfer:spu:write. In addition, the patch contains
> the following changes to remote packet support:
The TARGET_OBJECT_SPU support looks fine. I don't really like either
of these changes, though.
> - It adds a "length" argument to qXfer::write type packets. This is
> to make parsing of the packet easier, and to bring it in line with
> the 'X' packet format. (It also provides a bit of extra redundancy
> to detect transmission problems.)
It adds another case that stubs need to check for (length != length of
supplied data), and it's redundant. I have some code already written
to generate and parse binary packets without a specified length, if
you'd like me to post it. It's for the project I'm going to submit
once I finish with shared library lists - file transfer through
I think more redundancy is not what we need in an already chatty
protocol :-) And anyone using this to debug an SPU is probably going
to do so over a reliable link (pipe or TCP socket).
> - The remote_read_qxfer attempts to cache received end-of-object
> packets. However, this is a problem for some spufs objects as
> they can start out with no content (length zero), and acquire
> actual content later on. If remote_read_qxfer has already cache
> an end-of-object at lenght zero, future re-reads of the object
> will always return zero even if the object by now has actual
> content. To fix this we've added a CACHEABLE flag to the
> function and use it to disable the cache for spufs objects.
How about this simpler fix?
- if (rs->buf == 'l')
+ if (rs->buf == 'l' && offset + i > 0)
It's only supposed to trigger for the next part of the same read
operation. If we got no bytes, then the operation is already over.