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kernels/ksysfs.c: export kernel address bits

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This can be used by userspace to determine the address size of the
running kernel.
It frees userspace from having to interpret this information from the
UTS machine field.

Userspace implementation:
https://github.com/util-linux/util-linux/pull/1966

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20221221-address-bits-v1-1-8446b13244ac@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Weißschuh 2022-12-21 16:17:52 +00:00 committed by Greg Kroah-Hartman
parent e5da06b27f
commit 00142bfd5a
2 changed files with 19 additions and 0 deletions
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10
Documentation/ABI/testing/sysfs-kernel-address_bits Normal file
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@ -0,0 +1,10 @@
What: /sys/kernel/address_bit
Date: May 2023
KernelVersion: 6.3
Contact: Thomas Weißschuh <linux@weissschuh.net>
Description:
The address size of the running kernel in bits.
Access: Read
Users: util-linux

9
kernel/ksysfs.c
View File

@ -51,6 +51,14 @@ static ssize_t cpu_byteorder_show(struct kobject *kobj,
} }
KERNEL_ATTR_RO(cpu_byteorder); KERNEL_ATTR_RO(cpu_byteorder);
/* address bits */
static ssize_t address_bits_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sysfs_emit(buf, "%zu\n", sizeof(void *) * 8 /* CHAR_BIT */);
}
KERNEL_ATTR_RO(address_bits);
#ifdef CONFIG_UEVENT_HELPER #ifdef CONFIG_UEVENT_HELPER
/* uevent helper program, used during early boot */ /* uevent helper program, used during early boot */
static ssize_t uevent_helper_show(struct kobject *kobj, static ssize_t uevent_helper_show(struct kobject *kobj,
@ -233,6 +241,7 @@ static struct attribute * kernel_attrs[] = {
&fscaps_attr.attr, &fscaps_attr.attr,
&uevent_seqnum_attr.attr, &uevent_seqnum_attr.attr,
&cpu_byteorder_attr.attr, &cpu_byteorder_attr.attr,
&address_bits_attr.attr,
#ifdef CONFIG_UEVENT_HELPER #ifdef CONFIG_UEVENT_HELPER
&uevent_helper_attr.attr, &uevent_helper_attr.attr,
#endif #endif