Messages in this thread | | | Date | Tue, 28 Sep 2010 09:05:13 -0400 | From | Chris Metcalf <> | Subject | Re: asm-generic/unistd.h and glibc use of NR_ipc |
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(Adding libc-ports to the cc list.)
On 9/28/2010 4:40 AM, Arnd Bergmann wrote: > Chris Metcalf is using the generic unistd.h file on the tile architecture > and has a glibc port that should be easily portable to all future > architectures. There are a few of them getting ready to be merged > now (c6x, lm32, nios2, and some people have contacted me privately > for architectures I cannot name). > > I expect that all of them will just use the same syscall ABI and glibc > port.
I'm happy to provide some previews of the work I'm doing to interested parties.
One question for the libc folks is nomenclature. For now I'm using "sysdeps/unix/sysv/linux/generic" to hold the sources that are meant to be used for any architecture that uses Arnd's <asm-generic/unistd.h> along with the other asm-generic headers, e.g. <asm-generic/stat.h>. I've appended a list of the files that I've put in that directory to this email. Many of them are there just for handling missing "standard" syscalls in <asm-generic/unistd.h>; for example the "readlink" syscall becomes "readlinkat" in dl-origin.c, etc.
Is this the best name to use for the directory, though? In particular, glibc already uses "sysdeps/generic" in a slightly special sense to provide the fallback if no sysdeps override is available for a given file. But the Linux naming of "generic unistd.h" is pretty commonplace, so I assume that in the "linux/" hierarchy it is reasonably clear what that subdirectory means.
In practice, of course, there's still lots of architecture-specific code that is needed above and beyond the generic Linux subdirectory. Our 32-bit platform ("tile/tilepro") has an "Implies" file with unix/sysv/linux/generic and unix/sysv/linux/generic/wordsize-32; our 64-bit platform ("tile/tilegx") has an "Implies" file with unix/sysv/linux/generic and unix/sysv/linux/wordsize-64. Beyond that we have another 30-odd files in sysdeps/unix/sysv/linux/tile to implement the non-NPTL part of our glibc support, plus 50-odd files in sysdeps/tile.
I haven't provided an "nptl/sysdeps/unix/sysv/linux/generic/" directory since there wasn't anything obviously generic about the "tile" support I added for NPTL.
Another point where I'd appreciate guidance from libc-alpha is the sysctl() and ustat() APIs. The corresponding system calls are missing from <asm-generic/unistd.h>, since they are deprecated and their functionality is better provided by other means (/proc/sys, fstat). So I've simply had them return -1 with errno == ENOSYS. Is there any reason to think they merit more substantial work? One could imagine baking in some horrible mapping of "integer names" into path components for a sysctl() implementation and reading /proc/sys to provide results, or walking all of the mount points looking for a matching device number to pass a name to fstat(), but I'm not sure it's worth the bloat to the library.
I have a few patches for the platform-independent glibc code, mostly for things which are exposed in our platform but not in others. E.g. __readlink() in include/unistd.h returns the wrong type (int not ssize_t), and some of the standard Linux implementations of things like fxstat64.c need to be completely wrapped with "#ifndef XSTAT_IS_XSTAT64" so that fxstat.c can provide the alias, since all the stat structures are the same everywhere. I will submit some separate patches to libc-alpha for this.
Thanks in advance for any feedback. Please keep me cc'ed on any discussions of the generic Linux syscall ABI. Thanks!
sysdeps/unix/sysv/linux/generic/access.c sysdeps/unix/sysv/linux/generic/bits/fcntl.h sysdeps/unix/sysv/linux/generic/bits/sem.h sysdeps/unix/sysv/linux/generic/bits/stat.h sysdeps/unix/sysv/linux/generic/bits/typesizes.h sysdeps/unix/sysv/linux/generic/chmod.c sysdeps/unix/sysv/linux/generic/chown.c sysdeps/unix/sysv/linux/generic/lxstat.c sysdeps/unix/sysv/linux/generic/xstat.c sysdeps/unix/sysv/linux/generic/Versions sysdeps/unix/sysv/linux/generic/fxstatat.c sysdeps/unix/sysv/linux/generic/lchown.c sysdeps/unix/sysv/linux/generic/link.c sysdeps/unix/sysv/linux/generic/readlink.c sysdeps/unix/sysv/linux/generic/open.c sysdeps/unix/sysv/linux/generic/open64.c sysdeps/unix/sysv/linux/generic/pipe.c sysdeps/unix/sysv/linux/generic/poll.c sysdeps/unix/sysv/linux/generic/recv.c sysdeps/unix/sysv/linux/generic/rmdir.c sysdeps/unix/sysv/linux/generic/send.c sysdeps/unix/sysv/linux/generic/symlink.c sysdeps/unix/sysv/linux/generic/syscalls.list sysdeps/unix/sysv/linux/generic/sysdep.h sysdeps/unix/sysv/linux/generic/unlink.c sysdeps/unix/sysv/linux/generic/xmknod.c sysdeps/unix/sysv/linux/generic/sysctl.c sysdeps/unix/sysv/linux/generic/readlink_chk.c sysdeps/unix/sysv/linux/generic/ustat.c sysdeps/unix/sysv/linux/generic/wordsize-32/fcntl.c sysdeps/unix/sysv/linux/generic/wordsize-32/fstatfs.c sysdeps/unix/sysv/linux/generic/wordsize-32/ftruncate.c sysdeps/unix/sysv/linux/generic/wordsize-32/fxstat.c sysdeps/unix/sysv/linux/generic/wordsize-32/llseek.c sysdeps/unix/sysv/linux/generic/wordsize-32/lseek.c sysdeps/unix/sysv/linux/generic/wordsize-32/mmap.c sysdeps/unix/sysv/linux/generic/wordsize-32/posix_fadvise.c sysdeps/unix/sysv/linux/generic/wordsize-32/sendfile.c sysdeps/unix/sysv/linux/generic/wordsize-32/statfs.c sysdeps/unix/sysv/linux/generic/wordsize-32/truncate.c sysdeps/unix/sysv/linux/generic/brk.c sysdeps/unix/sysv/linux/generic/dl-origin.c sysdeps/unix/sysv/linux/generic/umount.c sysdeps/unix/sysv/linux/generic/creat.c sysdeps/unix/sysv/linux/generic/pause.c sysdeps/unix/sysv/linux/generic/Makefile sysdeps/unix/sysv/linux/generic/select.c sysdeps/unix/sysv/linux/generic/epoll_create.c sysdeps/unix/sysv/linux/generic/epoll_wait.c sysdeps/unix/sysv/linux/generic/inotify_init.c sysdeps/unix/sysv/linux/generic/dup2.c sysdeps/unix/sysv/linux/generic/mkdir.c sysdeps/unix/sysv/linux/generic/rename.c sysdeps/unix/sysv/linux/generic/utimes.c
-- Chris Metcalf, Tilera Corp. http://www.tilera.com
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