From: "Zhang, Ning A" <ning.a.zhang@intel.com>
To: "pombredanne@nexb.com" <pombredanne@nexb.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"kstewart@linuxfoundation.org" <kstewart@linuxfoundation.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: 3 version of MKDEV: kernel, uapi, libc, why?
Date: Wed, 11 Apr 2018 08:51:03 +0000 [thread overview]
Message-ID: <1523436662.1414.12.camel@intel.com> (raw)
Hi, Greg, Thomas
I find 3 version of MKDEV (actually 2 + makedev)
in include/linux/kdev_t.h
#define MINORBITS 20
#define MKDEV(ma,mi) (((ma) << MINORBITS) | (mi))
in inlcude/uapi/linux/kdev_t.h
#define MKDEV(ma,mi) ((ma)<<8 | (mi))
in Android bionic
#define makedev(__major, __minor) \
( \
(((__major) & 0xfffff000ULL) << 32) | (((__major) & 0xfffULL) <<
8) | \
(((__minor) & 0xffffff00ULL) << 12) | (((__minor) & 0xffULL)) \
)
if I use mknod("renderD128", S_IFCHR|0666, MKDEV(226, 128));
I get wrong device:
crw-rw-rw- 1 root graphics 0, 57984 2011-11-11 11:20 renderD128
if I use ("renderD128",S_IFCHR|0666, makedev(226, 128));
I get right device.
but, when I use: mknod("card0", S_IFCHR|0666, MKDEV(226, 0));
I can get right device.
BR.
Ning.
next reply other threads:[~2018-04-11 8:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 8:51 Zhang, Ning A [this message]
2018-04-11 10:04 ` 3 version of MKDEV: kernel, uapi, libc, why? gregkh
2018-04-12 1:45 ` Zhang, Ning A
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