Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / arch / x86 / Kconfig

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2623793..ac04d98 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -107,9 +107,9 @@ config X86
        select HAVE_ARCH_SOFT_DIRTY
        select CLOCKSOURCE_WATCHDOG
        select GENERIC_CLOCKEVENTS
-       select ARCH_CLOCKSOURCE_DATA if X86_64
+       select ARCH_CLOCKSOURCE_DATA
        select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
-       select GENERIC_TIME_VSYSCALL if X86_64
+       select GENERIC_TIME_VSYSCALL
        select KTIME_SCALAR if X86_32
        select GENERIC_STRNCPY_FROM_USER
        select GENERIC_STRNLEN_USER
@@ -1848,17 +1848,29 @@ config DEBUG_HOTPLUG_CPU0
          If unsure, say N.
 
 config COMPAT_VDSO
-       def_bool y
-       prompt "Compat VDSO support"
+       def_bool n
+       prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
        depends on X86_32 || IA32_EMULATION
        ---help---
-         Map the 32-bit VDSO to the predictable old-style address too.
+         Certain buggy versions of glibc will crash if they are
+         presented with a 32-bit vDSO that is not mapped at the address
+         indicated in its segment table.
 
-         Say N here if you are running a sufficiently recent glibc
-         version (2.3.3 or later), to remove the high-mapped
-         VDSO mapping and to exclusively use the randomized VDSO.
+         The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
+         and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
+         49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is
+         the only released version with the bug, but OpenSUSE 9
+         contains a buggy "glibc 2.3.2".
 
-         If unsure, say Y.
+         The symptom of the bug is that everything crashes on startup, saying:
+         dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
+
+         Saying Y here changes the default value of the vdso32 boot
+         option from 1 to 0, which turns off the 32-bit vDSO entirely.
+         This works around the glibc bug but hurts performance.
+
+         If unsure, say N: if you are compiling your own kernel, you
+         are unlikely to be using a buggy version of glibc.
 
 config CMDLINE_BOOL
        bool "Built-in kernel command line"