From: utzoo!decvax!duke!unc!mcnc!idis!george Newsgroups: net.unix-wizards Title: demand loading Article-I.D.: idis.177 Posted: Mon Jan 3 02:22:35 1983 Received: Tue Jan 4 02:51:14 1983 This site has a VAX running 4.0 BSD with a 2K byte block size. On this system demand load format is the default for "a.out" files. In such files the first block contains an eight word (i.e. 32 byte) header. The remainder of that block (i.e. 2016 bytes) is unused and contains zeros. I suspect that this wastes considerable storage space along with some processor and I/O time. I do not know whether there are different more recent "a.out" formats. I have a suggestion for a remedy. I have only given it brief consideration, so comments and discussion might be in order. The remedy involves a new demand load format in "a.out" files along with some corresponding kernel changes. The first eight words of the file contain the standard header. The ninth word will be discussed later. The tenth word of the file contains the tenth word of the load image. Succeeding words of the load image before "_etext" correspond to succeeding words in the file. The data segment follows normally. The ninth word contains an offset in the file to a location somewhere after the data segment image where the first nine words of the load image can be found. A copy of the first nine words of the executing image could be stored in some convenient data structure. Perhaps an enlarged "user" would due. George Rosenberg