Disabling sysroot

Disabling sysroot

[Marc Khouzam]

Hi,

in the doc it says:

   If you want to use `solib-search-path' instead of 
`sysroot', be sure to set `sysroot' to a nonexistent directory to prevent GDB 
from finding your host's libraries.

Is there a recommended way to turn off sysroot?
I can set it to something like /what/are/the/odds/of/this/dir/actually/existing
But it is not very elegant.
Can I set sysroot to "" or to "-" or some other symbol?
Or is setting sysroot to anything not starting with a / sufficient?

Thanks

Re: Disabling sysroot

[Daniel Jacobowitz]

On Wed, Jun 04, 2008 at 09:34:02AM -0400, Marc Khouzam wrote:
> Hi,
> 
> in the doc it says:
> 
>    If you want to use `solib-search-path' instead of 
> `sysroot', be sure to set `sysroot' to a nonexistent directory to prevent GDB 
> from finding your host's libraries.
> 
> Is there a recommended way to turn off sysroot?
> I can set it to something like /what/are/the/odds/of/this/dir/actually/existing
> But it is not very elegant.

I use /dev/null, which will never be a directory.

There's no way to disable sysroot; setting it to empty is the same as
not setting it at all, i.e. use the host's libraries.

> Or is setting sysroot to anything not starting with a / sufficient?

A relative path may be a valid sysroot; GDB will search from its
current directory (there's no special check for absolute paths).

-- 
Daniel Jacobowitz
CodeSourcery

RE: Disabling sysroot

[Marc Khouzam]

/dev/null it is.

Thanks


-----Original Message-----
From: Daniel Jacobowitz [mailto:drow@false.org]
Sent: Wed 6/4/2008 11:13 AM
To: Marc Khouzam
Cc: gdb@sourceware.org
Subject: Re: Disabling sysroot
 
On Wed, Jun 04, 2008 at 09:34:02AM -0400, Marc Khouzam wrote:
> Hi,
> 
> in the doc it says:
> 
>    If you want to use `solib-search-path' instead of 
> `sysroot', be sure to set `sysroot' to a nonexistent directory to prevent GDB 
> from finding your host's libraries.
> 
> Is there a recommended way to turn off sysroot?
> I can set it to something like /what/are/the/odds/of/this/dir/actually/existing
> But it is not very elegant.

I use /dev/null, which will never be a directory.

There's no way to disable sysroot; setting it to empty is the same as
not setting it at all, i.e. use the host's libraries.

> Or is setting sysroot to anything not starting with a / sufficient?

A relative path may be a valid sysroot; GDB will search from its
current directory (there's no special check for absolute paths).

-- 
Daniel Jacobowitz
CodeSourcery

Re: Disabling sysroot

[Eli Zaretskii]

> Date: Wed, 4 Jun 2008 11:13:13 -0400
> From: Daniel Jacobowitz <drow@false.org>
> Cc: gdb@sourceware.org
> 
> On Wed, Jun 04, 2008 at 09:34:02AM -0400, Marc Khouzam wrote:
> > Hi,
> > 
> > in the doc it says:
> > 
> >    If you want to use `solib-search-path' instead of 
> > `sysroot', be sure to set `sysroot' to a nonexistent directory to prevent GDB 
> > from finding your host's libraries.
> > 
> > Is there a recommended way to turn off sysroot?
> > I can set it to something like /what/are/the/odds/of/this/dir/actually/existing
> > But it is not very elegant.
> 
> I use /dev/null, which will never be a directory.

Is this worth mentioning in the manual?

RE: Disabling sysroot

[Marc Khouzam]

 
> > I use /dev/null, which will never be a directory.
> 
> Is this worth mentioning in the manual?

It would have been helpful for me, so I vote for yes :-)

It would be even nicer to have a way to 'turn off' sysroot
for this case.  Something like "unset sysroot".  I'm not
sure if "unset" is something that GDB supports.

Marc

Re: Disabling sysroot

[Daniel Jacobowitz]

On Thu, Jun 05, 2008 at 11:07:59AM -0400, Marc Khouzam wrote:
>  
> > > I use /dev/null, which will never be a directory.
> > 
> > Is this worth mentioning in the manual?
> 
> It would have been helpful for me, so I vote for yes :-)
> 
> It would be even nicer to have a way to 'turn off' sysroot
> for this case.  Something like "unset sysroot".  I'm not
> sure if "unset" is something that GDB supports.

It is, but unsetting sysroot does not mean what you want.  Without a
sysroot, libraries are searched for in the root filesystem on the
host.  You want to actually disable searching by full path; gdb has no
option for that.

-- 
Daniel Jacobowitz
CodeSourcery

RE: Disabling sysroot

[Marc Khouzam]

 
> > It would be even nicer to have a way to 'turn off' sysroot
> > for this case.  Something like "unset sysroot".  I'm not
> > sure if "unset" is something that GDB supports.
> 
> It is, but unsetting sysroot does not mean what you want.  Without a
> sysroot, libraries are searched for in the root filesystem on the
> host.  You want to actually disable searching by full path; gdb has no
> option for that.

From what I understand, it would be nice if unset sysroot disabled sysrtoot, 
while an explicit set sysrtoot "/" be used to search from the root.
But, for the sake of backwards compatibility, this should probably
be left alone and /dev/null used for sysrtoot to disable it.

Marc

RE: Disabling sysroot

[Paul Koning]

>>>>> "Marc" == Marc Khouzam <marc.khouzam@ericsson.com> writes:

 >> > It would be even nicer to have a way to 'turn off' sysroot > for
 >> this case.  Something like "unset sysroot".  I'm not > sure if
 >> "unset" is something that GDB supports.
 >> 
 >> It is, but unsetting sysroot does not mean what you want.  Without
 >> a sysroot, libraries are searched for in the root filesystem on
 >> the host.  You want to actually disable searching by full path;
 >> gdb has no option for that.

 Marc> From what I understand, it would be nice if unset sysroot
 Marc> disabled sysrtoot, while an explicit set sysrtoot "/" be used
 Marc> to search from the root.  But, for the sake of backwards
 Marc> compatibility, this should probably be left alone and /dev/null
 Marc> used for sysrtoot to disable it.

There should be a user-friendly way to disable sysroot, and that
should be on by default in a cross-gdb.

       paul