Re: [RFC] File-I/O, target access to host file system via gdb remote protocol enhancement

[Daniel Jacobowitz <drow@mvista.com>]

On Mon, Nov 11, 2002 at 01:13:54PM +0100, Corinna Vinschen wrote:
> Hi,
> 
> this RFC tries to introduce a remote protocol enhancement, which
> already has been implemented at Red Hat.  The idea is to allow
> the remote target (which likely has no own file system at all)
> to access the host file system to store and retrieve data from
> a gdb session, as if the hosts filesystem is local to the target.

This is a great thing.  I remember using similar functionality both for
debugging and for running certain unnamed industry benchmarks...

> A second part of this implementation is to map the basic stdio
> streams (file descriptors 0-2) to the gdb console, to enable
> the user to serve a remote target application interactively.
> This should work in gdb's CLI as well as in the GUI.

I like this one too; but I'm not sure that I like linking it to the
remote-syscall interface.  Implementation-wise, that's the most useful
method for a stub like RedBoot; but for a larger system like gdbserver,
it's useful to allocate the program a normal pseudo-terminal as if it
had a console.  And to do character rather than line I/O.

As I'm sure Andrew will remind me, my suggestion doesn't fit the
current remote protocol very well; it's not synchronous enough for one
thing.  So don't take this as an objection, and I'll come back to
proper remote console support a little later.  This'll be a nice
starting point.

> B.3 struct stat
> 
>   The buffer of type struct stat used by the target and GDB is defined
>   as follows:
> 
>     struct stat {
> 	unsigned int  st_dev;      /* device */
> 	unsigned int  st_ino;      /* inode */
> 	mode_t        st_mode;     /* protection */
> 	unsigned int  st_nlink;    /* number of hard links */
> 	unsigned int  st_uid;      /* user ID of owner */
> 	unsigned int  st_gid;      /* group ID of owner */
> 	unsigned int  st_rdev;     /* device type (if inode device) */
> 	unsigned long st_size;     /* total size, in bytes */
> 	unsigned long st_blksize;  /* blocksize for filesystem I/O */
> 	unsigned long st_blocks;   /* number of blocks allocated */
> 	time_t        st_atime;    /* time of last access */
> 	time_t        st_mtime;    /* time of last modification */
> 	time_t        st_ctime;    /* time of last change */
>     };
> 
>   The integral datatypes are conforming to the definition in B.1 so this
>   structure is of size 64 bytes.

Ick, 32-bit st_ino... why bother to transfer it if you say "no meaning
for the target"?

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer