Re: [PATCH] Make ftrace tests work with remote targets

[Simon Marchi <simon dot marchi at ericsson dot com>]

On 16-03-29 06:46 PM, Pedro Alves wrote:
> On 03/03/2016 09:22 PM, Simon Marchi wrote:
>> --- a/gdb/testsuite/lib/gdb.exp
>> +++ b/gdb/testsuite/lib/gdb.exp
>> @@ -3374,7 +3374,7 @@ proc gdb_compile {source dest type options} {
>>      # dynamically load one by basename, we must specify rpath.  If we
>>      # are using a remote host, DejaGNU will link to the shared library
>>      # using a relative path, so again we must specify an rpath.
>> -    if { $shlib_load || ($shlib_found && [is_remote target]) } {
>> +    if { $shlib_load || $shlib_found } {
> 
> I think the comment above needs updating.

What about:

     # Because we link with libraries using their basename, we may need
     # (depending on the platform) to set a special rpath value, to allow
     # the executable to find the libraries it depends on.

>>  	    lappend link_options "additional_flags=-Wl,--out-implib,${name}.a"
>> -	} elseif [is_remote target] {
>> +	} else {
>>  	    # By default, we do not set the soname.  This causes the linker
> 
> Likewise.

What about:

             # Set the soname of the library.  This causes the linker on ELF
             # systems to create the DT_NEEDED entry in the executable referring
             # to the soname of the library, and not its absolute path.  This
             # (using the absolute path) would be problem when testing on a
             # remote target.
             #
             # In conjunction with setting the soname, we add the special
             # rpath=$ORIGIN value when building the executable, so that it's
             # able to find the library in its own directory.


>>  proc gdb_load_shlibs { args } {
>> -    if {![is_remote target]} {
>> -	return
>> -    }
>> +    if {[is_remote target]} {
>> +	foreach file $args {
>> +	    # When the target is remote, we simply send the file to the target.
>> +	    gdb_download [shlib_target_file $file]
>> +	}
>> +    } else {
>> +	foreach from $args {
>> +	    # When the target is native, we copy the files to the test directory
>> +	    # (next to the executable), except if that's already where it is.
>> +	    set to [standard_output_file [file tail $from]]
> 
> I'd think it better to make the gdb_download path work for native
> testing as well.  WDYT?  E.g., make shlib_target_file default to
> return the test directory path?

If I understand correctly, gdb_download would take a local file path and take
care of transferring that file to the "runtime test directory", whether it's
local or remote.  If the target is local, it checks whether $src == $dest, and
copies the file if not.  Basically, the same as my implementation of
gdb_load_shlibs, just not limited to shlibs.

I am not sure if "make shlib_target_file default to return the test directory path?"
would be ok.  I think it's meant to return the local file path to download to the
target.  So gdb_load_shlibs would then become:

proc gdb_load_shlibs { args } {
    foreach file $args {
        gdb_download [shlib_target_file $file]
    }
}

I just tested it quickly and it seems to work fine.  But I also noticed that there
might be some overlap in feature between gdb_download and gdb_remote_download, so
perhaps I can try to merge them, WDYT?

>> # Even if the target supplies full paths for shared libraries,
>> # they may not be paths for this system.
>> gdb_test "set solib-search-path [file dirname [lindex $args 0]]" "" ""
> 
> Can we skip this command on native testing?
> 
> I'm worried that that command might paper over, or cause, issues with
> sysroot / dso path lookup.  Normal native debugging usage will not specify
> that command, so if we could avoid it, I'd prefer it, on grounds of
> testing what users normally use.  

Makes sense.  I'll add that, with a comment explaining why.

Thanks!

Simon