On 08/02/17 13:43, Konstantin Belousov wrote:
On Wed, Aug 02, 2017 at 01:27:50PM +0200, Hans Petter Selasky wrote:
On 08/02/17 13:17, Konstantin Belousov wrote:
But y must be dev_t.
Sure, but "struct cdev" 's si_drv0 is only "int" . How can it contain
dev_t ?
Why should it contain dev_t ?
Linux KPI abused that field it seems.
Hi,
The LinuxKPI uses si_drv0 to contain the output from mkdev(). Before the
mkdev() function would fit into 32-bits. Now it is 64-bits.
I can fix the LinuxKPI bits this time. We can store this information in
si_drv1->xxx instead of using si_drv0 and dev2unit().
Lets change the focus of the discussion.
You cited the
struct linux_cdev *
linux_find_cdev(const char *name, unsigned major, unsigned minor)
function which finds cdev (or some mockup of the native cdev) by major/minor.
Where does these major/minor numbers come from ?
The major number is in the range 0..255 and decides the type of device.
The minor number is in the range 0..255 aswell typically and defines a
unique number for each LinuxKPI created character device.
I mean that if they are contructed as major(struct stat.st_rdev) and
minor(struct stat.st_rdev), then even the original code looks wrong
without the ino64 addition. Since devfs reports the internal inode
number into st_rdev, which formally is not accessible outside the devfs
filesystem. So should the code for linux_find_cdev() changed to match
cdevs against inode number ?
These numbers do not come from any user-visible files. They are just
used internally in the kernel to pass around information.
cdp_inode is serially generated so on real machine it is really a small
number for any /dev node. You can watch that by ls -l /dev.
Sure.
While at it, I found that contrib/mknod/pack_dev.c, still has hardcoded
references to the old makedev():
contrib/mknod/pack_dev.c:#define makedev_freebsd(x,y) ((portdev_t)((((x)
<< 8) & 0x0000ff00) | \
contrib/mknod/pack_dev.c: dev = makedev_freebsd(numbers[0],
numbers[1]);
Same goes for: contrib/libarchive/libarchive/archive_pack_dev.c
And if you "grep -r makedev /usr/src" you'll find more.
--HPS
_______________________________________________
svn-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
