From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: GNU C Library <libc-alpha@sourceware.org>
Cc: nd@arm.com
Subject: aarch64: add HWCAP_ATOMICS to HWCAP_IMPORTANT
Date: Thu, 19 Apr 2018 11:51:00 -0000 [thread overview]
Message-ID: <1d8eb765-e147-534e-ed1e-daa8deb8d5a7@arm.com> (raw)
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This enables searching shared libraries in atomics/ when the hardware
supports LSE atomics of armv8.1 so one can provide optimized variants
of libraries in a portable way.
LSE atomics does not affect library abi, the new instructions can
interoperate with old ones.
I'm not familiar with how this feature of the dynamic linker is used
in practice by distros or others so comments are welcome.
2018-04-19 Szabolcs Nagy <szabolcs.nagy@arm.com>
* sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h (HWCAP_IMPORTANT): Add
HWCAP_ATOMICS.
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diff --git a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h
index 6887713149..4530cc2159 100644
--- a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h
+++ b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h
@@ -27,9 +27,9 @@
/* We cannot provide a general printing function. */
#define _dl_procinfo(type, word) -1
-/* HWCAP_CPUID should be available by default to influence IFUNC as well as
- library search. */
-#define HWCAP_IMPORTANT HWCAP_CPUID
+/* Default hwcap_mask setting, affects the library search path and cpu_features
+ used by glibc internal IFUNCs when the selected hwcaps are available. */
+#define HWCAP_IMPORTANT (HWCAP_CPUID | HWCAP_ATOMICS)
static inline const char *
__attribute__ ((unused))
next reply other threads:[~2018-04-19 11:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-19 11:51 Szabolcs Nagy [this message]
2018-04-19 14:38 ` Adhemerval Zanella
2018-04-19 17:07 ` Szabolcs Nagy
2018-04-19 19:25 ` Adhemerval Zanella
2018-04-30 15:27 ` Carlos O'Donell
2018-04-19 16:08 ` Steve Ellcey
2018-04-19 16:58 ` Szabolcs Nagy
2018-04-30 15:34 ` Carlos O'Donell
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