On Wed, Jun 18, 2014 at 12:22 AM, Andy Lutomirski <[email protected]> wrote: > On Tue, Jun 17, 2014 at 8:48 PM, H. Peter Anvin <[email protected]> wrote: >> On 06/17/2014 08:45 PM, Andy Lutomirski wrote: >>> On Tue, Jun 17, 2014 at 3:54 PM, Andy Lutomirski <[email protected]> >>> wrote: >>>> Just a heads up: gdb can't debug the vdso on 3.16-rc1. I filed a bug: >>>> >>>> https://sourceware.org/bugzilla/show_bug.cgi?id=17064 >>>> >>>> We may need to extend the fake section header hack to all vdso >>>> versions and stick the ELF notes in there. >>> >>> I have a semi-working implementation of a workaround, bit it adds a >>> fair amount of extra crud to the image, and it's pushing my >>> configuration past a page boundary. I suspect that, if we're willing >>> to abuse the ELF format a bit more, I can get the overhead down, >>> though. >>> >>> Are we okay with regressing here until binutils gets fixed? >>> >> >> Probably not... although I guess it depends just how bad it really is. > > AFAICT the only issue is that gdb will fail to find installed debug > info on systems that install it into .build-id, which AFAIK means > Fedora and similar users who install kernel RPMs. This won't effect > anyone who installs their own kernel, since it never worked correctly > for those users anyway.
For some reason I thought SLES/OpenSUSE did build-id as well. > Fortunately, Fedora ought to be able to update its gdb and/or binutils > rpm by the time that 3.16 kernel RPMs show up. Josh, is this > workable? In my experience, I've never had a sourceware.org bug Getting binutils fixed in rawhide typically isn't a problem if the reporter and upstream are persistent. Getting it fixed in a more stable Fedora release is a bit more work and really depends on how invasive the fix is. > fixed, but I have had bugzilla.redhat.org bugs fixed. I'm looking at > the binutils code, and I'm kind of scared of it. Also, I don't have > an FSF copyright assignment on file. > > I filed this Fedora bug: > > https://bugzilla.redhat.com/show_bug.cgi?id=1110598 > > Let's see what happens. Can we give this a little while? I think that really depends on who all is using build-id for their debuginfo stuff and how much upstream cares about breaking them. Even if it's contained to Fedora derived distros, getting binutils fixed in RHEL for this is much harder. I have no idea how SLES/OpenSUSE would contain this if they are using build-id. > I wrote this: > > https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/log/?h=x86/vdso_sections > > but it's bad: I'm not allocating space properly, so it doesn't > reliably build. Also, it wastes space, and I'd rather just get rid of > this crap. The "if/when binutils gets fixed" is really the crux of the issue. Unless the upstream kernel puts a hard requirement on a fixed binutils version, we can't really depend on people having a fixed binutils. If that code were to get added, it would like stay for a very long time. josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
