[Crash-utility] mod -S and debuginfo kernel rpm

[Michael Holzheu]

Hi Dave,

Am Mittwoch, den 22.04.2009, 13:57 -0400 schrieb Dave Anderson:
> ----- "Michael Holzheu" <holzheu at linux.vnet.ibm.com> wrote:
> > 
> > I thought that you where suggesting to search only in
> > <-S dir>/lib/modules.. and <-S dir>/usr/lib/debug/..
> > 
> > As I said before, "mod -S <dir>" currently searches in all
> > subdirectories of <dir>.
> 
> Right, that's what my follow-up email explained more thoroughly:
> 
> > And just to clarify this further.  When "mod -S [directory]" is entered,
> > the search will be made starting from [directory].  In other words,
> > it will not immediately append "/lib/modules" and "/usr/lib/debug/lib/modules"
> > onto [directory].  It's just that that's where they'll be found
> > if the double-rpm2cpio were done.  
> >
> > Conceivably you could just dump all the .ko and .ko.debug files into
> > the one flat [directory], and it will find them right away.
> 
> But that leads to another issue.  
> 
> Suppose a directory target was set up with double-rpm2cpio, such that,
> for example, the ext3.ko module would be found here:
> 
>   <target-dir>/lib/modules/2.6.18-128.el5/kernel/fs/ext3/ext3.ko
> 
> The gdb algorithm currently searches for ext3.ko.debug in these 3
> directories, in this order:
> 
>  A. <target-dir>/lib/modules/2.6.18-128.el5/kernel/fs/ext3
>  B. <target-dir>/lib/modules/2.6.18-128.el5/kernel/fs/ext3/.debug
>  C. /usr/lib/debug/lib/modules/2.6.18-128.el5/kernel/fs/ext3
> 
> So it doesn't find it in the "double-rpm2cpio" layout.  And so my
> proposal would add this additional search path:
> 
>  D. <target-dir>/usr/lib/debug/lib/modules/2.6.18-128.el5/kernel/fs/ext3
> 
> and it would find it.  It's essentially "C", but with <target-dir>
> prepended to the search path.
> 
> But it *does* require an analogous relative file tree layout.
> 
> So if for example, all .ko and .ko.debug files were just dumped in
> the <target-dir>:
> 
>   (1) ext3.ko would be found in <target-dir>
>   (2) ext3.ko.debug would be found in <target-dir> -- using gdb algorithm "A".
> 
> But if ext3.ko was located in:
> 
>   <target-dir>/lib/modules/2.6.18-128.el5/kernel/fs/ext3
> 
> then the proposed "D" algorithm would find ext3.ko.debug in:
> 
>   <target-dir>/usr/lib/debug/lib/modules/2.6.18-128.el5/kernel/fs/ext3
> 
> But it would *only* find it in the directory above.  And that's because
> the gdb algorithms create fully-qualified directory pathnames based
> upon the full path to the stripped .ko file, and then looks in those
> directories to accomplish "A", "B" and "C".
> 
> So there would be that restriction as to the *relative* locations of
> the .ko and .ko.debug files.  But I don't think that's really all that
> burdensome.  
> 
> Comments?

I think that's a good proposal!

Michael