[Bug remote/28489] Allow caching of remote objfiles

["simark at simark dot ca" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=28489

--- Comment #11 from Simon Marchi <simark at simark dot ca> ---
(In reply to Tom Tromey from comment #7)
> It occurred to me that to make this work, we'll need a new protocol
> extension (no big deal) and gdbserver will have to know how to
> extract the build id (a bigger deal).

I think it would be fine for GDBserver to learn how to extract build-ids.  It
should be quite fast, and including a build-id field in the shared library list
does not increase much the data transferred.  I don't know if GDB needs to
download the libraries up front for other reasons though.

Otherwise, in theory, GDB should be able to extract the build-id of remote
libraries by reading just the necessary bits (without downloading the whole
file), using remote file-io.  The upside is that it should work with the
existing protocol, but the downside is that it would do many small requests to
read small bits here and there (reading the ELF header, then looking through
notes), so it adds a lot of back and forth, and the latency adds up.

> I guess a different idea would be to construct a cached directory
> tree that works like a sysroot, and use the existing remote
> protocol stat capability to decide when to update a file. In this
> approach, build ids just would not be used (or, rather, would be
> used to locate remote debuginfo files).

Using modification times to know when cached files are stale, or something
else?  That seems difficult to manage.  Do you make one directory per remote? 
You could connect to 10.0.0.11:8888 and it's some system, and later connect to
10.0.0.11:8888, and it's another system.  How do you detect that?

-- 
You are receiving this mail because:
You are on the CC list for the bug.