From: Roland McGrath Subject: Re: Future of ext2 support in the Hurd? Date: Sun, 12 Aug 2007 20:13:36 -0700 (PDT) Message-ID: <20070813031336.76A051C0C8@topped-with-meat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, bug-hurd@gnu.org To: "Theodore Ts'o" Return-path: In-Reply-To: Theodore Ts'o's message of Sunday, 12 August 2007 17:40:00 -0400 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: bug-hurd-bounces+gnu-bug-hurd=m.gmane.org@gnu.org Errors-To: bug-hurd-bounces+gnu-bug-hurd=m.gmane.org@gnu.org List-Id: linux-ext4.vger.kernel.org The license issues are not directly apropos to the main subject of cooperation on supporting a particular disk format, so I'll leave that aside. Let us discuss the future of the EXT2_OS_HURD variant of ext2 format. Indeed some people do use the Hurd and they all do rely on the EXT2_OS_HURD format support in e2fsprogs. It's the intended plan to migrate away from EXT2_OS_HURD format and use a strict subset of the ext2 format features used natively by Linux ext2fs (in theory eventually that whole set). The Hurd-specific data now stored in inode fields in EXT2_OS_HURD format would instead be stored in ext2 xattr format. The extent of cooperation then required between ext2 format authorities and Hurd developers is assigning an EXT2_XATTR_INDEX_* number to correspond to the "gnu." prefix. The conventions for formats and semantics of attributes with this prefix will be maintained by the GNU Project. Of course, I've been saying this was the plan for several years, and very few steps of that migration have begun. (You're probably not eager to see my dusty patches for Linux ext2fs to support EXT2_OS_HURD format by mapping its special data items to virtual xattrs with gnu.* names. :-) If it is important to you and you would like to state a quasi-formal schedule to deprecate EXT2_OS_HURD format (not instantaneously), we can work with that. We'd hope for a decent interval of backward compatibility support in e2fsck. (The Hurd code will probably continue to support the old format indefinitely.) Hurd developers can make a small push to get our ext2fs code supporting the xattr format encoding of Hurd-specific metadata. If you're feeling especially charitable, you could provide format conversion support in e2fsprogs. Thanks, Roland