Re: [ECOS] About "File I/O operations via GDB"

[Nick Garnett <nickg at ecoscentric dot com>]

"Vincent Leclaire" <vleclaire@awox.com> writes:

> Hi everybody,
> 
> Does anyone have experience with this option ? My goal is to try to
> route "fopens" (and the like) executed on the target to the debugging
> host filesystem, presumably using GDB.
> 
> (target is an i386 pc but will change in the future, that's why I try to
> simulate without using a disk!)
> 
> I've searched the lists. I've searched the Net. Nothing clear about
> this, especially on non-ARM targets. Here's a snapshot of my knowledge
> :-)
> 
> * I understand it's about Redboot syscalls and virtual vectors. Apart
> from selecting the option what is needed ? I think I don't have problems
> w/ virtual vectors since the "rest" seems to work. How can I make sure
> my app is able to talk to Redboot if needed ?
> 
> * I guess the app (or the stdiolib) must be recompiled to map file i/o
> operations, but I was unable to find info about the way to do it (on my
> "i386-all" setup I cannot select the "file operations via GDB"
> checkbox).
> 
> * The comment for the option says "doable only through RedBoot syscall".
> Does it mean it must be hard-coded in the program by hand ? How do you
> call those services (I know there are SYSCALL macros for this) ?
> 
> * Any special stuff for ARM targets (what is newlib / libgloss BTW) ?
> 
> * What about gdb/Insight special configuration on the debugging host ?
> 
> Thanks for any pointers you can provide !

These operations are there to support stand-alone applications built
using just the gcc toolchain. They cannot be used from eCos.

The GCC toolchain contains its own stand-alone C library, called
newlib, which ultimately executes trap or syscall instructions to
handle any IO. RedBoot contains support to handle these and pass them
back to GDB. For this to work the appropriate support needs to be
included in GDB, which is not the default for most targets.


-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com      The eCos and RedBoot experts


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