Some embedded systems with tightly controlled userspace have no use
for /dev/urandom, and could benefit from the size savings gained by
omitting it. Add a new EMBEDDED config option to disable it.
bloat-o-meter (based on tinyconfig):
add/remove: 0/2 grow/shrink: 1/0 up/down: 77/-212 (-135)
function old new delta
sys_getrandom 211 288 +77
urandom_read 96 - -96
urandom_fops 116 - -116
Signed-off-by: Tom Zanussi <tom.zanu...@linux.intel.com>
---
drivers/char/Kconfig | 11 +++++++++++
drivers/char/mem.c | 2 ++
drivers/char/random.c | 2 ++
3 files changed, 15 insertions(+)
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 9416b7e..1af4551 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -78,6 +78,17 @@ config DEVRANDOM
disabled on systems that will never use it in production,
such as many embedded systems. When in doubt, say "Y".
+config DEVURANDOM
+ bool "/dev/urandom virtual device support" if EMBEDDED
+ depends on DEVMEM_BASE
+ default y
+ help
+ Say Y here if you want to support the /dev/urandom
+ device. The /dev/urandom device is the nonblocking userspace
+ interface to the kernel random number generator, and can be
+ disabled on systems that will never use it in production,
+ such as many embedded systems. When in doubt, say "Y".
+
config SGI_SNSC
bool "SGI Altix system controller communication support"
depends on (IA64_SGI_SN2 || IA64_GENERIC)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index f226714..5315f63 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -829,7 +829,9 @@ static const struct memdev {
#ifdef CONFIG_DEVRANDOM
[8] = { "random", 0666, &random_fops, NULL },
#endif
+#ifdef CONFIG_DEVURANDOM
[9] = { "urandom", 0666, &urandom_fops, NULL },
+#endif
#ifdef CONFIG_PRINTK
[11] = { "kmsg", 0644, &kmsg_fops, NULL },
#endif
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 8547056..7e5a423 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1520,6 +1520,7 @@ const struct file_operations random_fops = {
};
#endif
+#ifdef CONFIG_DEVURANDOM
const struct file_operations urandom_fops = {
.read = urandom_read,
.write = random_write,
@@ -1527,6 +1528,7 @@ const struct file_operations urandom_fops = {
.fasync = random_fasync,
.llseek = noop_llseek,
};
+#endif
SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
unsigned int, flags)
--
1.9.3
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