Mailinglist Archive: opensuse-buildservice (124 mails)

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[opensuse-buildservice] Do we have exec-shield as well as enabled during build?
Hi,

just seen such build messages on aarch64 for GNU Emacs:

[ 1604s] **************************************************
[ 1604s] Warning: Your system has a gap between BSS and the
[ 1604s] heap (418602288 bytes). This usually means that exec-shield[
1519.794139] pgd = ffff8001f2320000
[ 1604s]
[ 1604s] [ 1519.828659] [00949000] *pgd=0000000232181003,
*pud=000000022ec05003or something similar is in effect. The dump may,
*pmd=00000002330f4003, *pte=0000000000000000
[ 1604s]
[ 1604s] fail because of this. See the section about
[ 1604s] exec-shield in etc/PROBLEMS for more information.

and indeed on emacs-25.1/etc/PROBLEMS I read

| Another issue is that in Red Hat Linux kernels, Exec-shield is enabled by
| default, and this creates a different memory layout. Emacs should
| handle this at build time, but if this fails the following
| instructions may be useful. Exec-shield is enabled on your system if
|
| cat /proc/sys/kernel/exec-shield
|
|prints a nonzero value. You can temporarily disable it as follows:
|
| echo 0 > /proc/sys/kernel/exec-shield

similar for randomize_va_space:

| To work around the ASLR problem in either an older or a newer kernel,
| you can temporarily disable the feature while building Emacs. On
| GNU/Linux you can do so using the following command (as root).
|
| echo 0 > /proc/sys/kernel/randomize_va_space
|
| You can re-enable the feature when you are done, by echoing the
| original value back to the file.
|
| Alternatively, you can try using the 'setarch' command when building
| temacs like this, where -R disables address space randomization:
|
| setarch $(uname -m) -R make

That is if we support exec-shield and/or randomize_va_space I'd like to
be able to disable this in the build environment for GNU emacs as well as
e.g. for clisp and maybe other packages.

Werner

--
"Having a smoking section in a restaurant is like having
a peeing section in a swimming pool." -- Edward Burr
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