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What is the point of padding?

开发者 https://www.devze.com 2023-02-01 03:53 出处：网络

In particular, I\'m reading into the Mach-O binary file format for Intel 32 on OS X. After the FAT header there is a whole bunch of padding before the offset of the first archive. What is the point of

相关专题：binary mach-o machine-code universal

In particular, I'm reading into the Mach-O binary file format for Intel 32 on OS X. After the FAT header there is a whole bunch of padding before the offset of the first archive. What is the point of all this p开发者_开发问答adding?

To be more specific, there is upwards of 4000 bytes of padding between the FAT header and the first archive (in particular, the mach_header). Why include all these extra bytes?! Is OS X fond of adding 4 KB to all their universal binaries?

My guess is that this is added to make sure that the next segment start at a 4096 byte boundary, the size of a virtual memory page on x86. Virtual memory on x86 (and PCC) is allocated in blocks which is a multiple of 4kB in size. Keeping the disc format compatible with memory page size makes demand loading easier to implement.