linux-generic: add a README

diff --git a/ChangeLog b/ChangeLog
index d449323..b9b3c2c 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-19  Chris Metcalf  <cmetcalf@ezchip.com>
+
+       * sysdeps/unix/sysv/linux/generic/README: New file.
+
 2015-03-18  Joseph Myers  <joseph@codesourcery.com>
 
        [BZ #18138]

diff --git a/sysdeps/unix/sysv/linux/generic/README b/sysdeps/unix/sysv/linux/generic/README
new file mode 100644 (file)
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--- /dev/null
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+This hierarchy supports Linux systems using the new
+asm-generic/unistd.h, which removes many familiar old syscalls.  For
+example, to implement open(), newer Linux architectures require glibc
+to invoke the __NR_openat syscall with AT_FDCWD.  This hierarchy
+provides all those implementations.
+
+It also provides support for 32-bit platforms using the 64-bit kernel
+syscall APIs, as the 32-bit ones are no longer provided.  Note that
+newer ILP32 environments (x32 or AArch64:ILP32, for example) are
+converting to use more 64-bit types in kernel syscalls, so that aspect
+of this support is in more flux as of this writing.