Do not export AT_CLKTCK when emulating Linux kernel prior

to 2.4.0, as it has appeared in the 2.4.0-rc7 first time.
Being exported, AT_CLKTCK is returned by sysconf(_SC_CLK_TCK),
glibc falls back to the hard-coded CLK_TCK value when aux entry
is not present.

Glibc versions prior to 2.2.1 always use hard-coded CLK_TCK value.

For older applications/libc's which depends on hard-coded CLK_TCK
value user should set compat.linux.osrelease less than 2.4.0.

Approved by:	kib (mentor)

1 files changed, 11 insertions, 1 deletions

diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index 0a3d297..186e14c 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -255,7 +255,17 @@ elf_linux_fixup(register_t **stack_base, struct image_params *imgp)
 	pos = *stack_base + (imgp->args->argc + imgp->args->envc + 2);
 
 	AUXARGS_ENTRY(pos, LINUX_AT_HWCAP, cpu_feature);
-	AUXARGS_ENTRY(pos, LINUX_AT_CLKTCK, stclohz);
+
+	/*
+	 * Do not export AT_CLKTCK when emulating Linux kernel prior to 2.4.0,
+	 * as it has appeared in the 2.4.0-rc7 first time.
+	 * Being exported, AT_CLKTCK is returned by sysconf(_SC_CLK_TCK),
+	 * glibc falls back to the hard-coded CLK_TCK value when aux entry
+	 * is not present.
+	 * Also see linux_times() implementation.
+	 */
+	if (linux_kernver(curthread) >= LINUX_KERNVER_2004000)
+		AUXARGS_ENTRY(pos, LINUX_AT_CLKTCK, stclohz);
 	AUXARGS_ENTRY(pos, AT_PHDR, args->phdr);
 	AUXARGS_ENTRY(pos, AT_PHENT, args->phent);
 	AUXARGS_ENTRY(pos, AT_PHNUM, args->phnum);