changes

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

	changes to Ken's file server to make this 63-bit file server

		Geoff Collyer
		July—October 2004

note: 2⁶⁳=9,223,372,036,854,775,808 or 8EB (9.2×10ⁱ⁸)

• identified longs that refer to offsets, sizes and block numbers, and
changed them to type Off (vlong); fixed all print formats to match.
fixed byte-swapping for the 'x' config to match.

• fixed VLONG 9p1 message packing and unpacking macros to actually
handle 64-bit offsets and sizes.

• implemented triple-indirect blocks.  affected code in
	dev/cw.c	port/con.c	port/dentry.c	port/sub.c
	port/chk.c	port/console.c	port/portdat.h

• Fri Aug  6 16:50:59 PDT 2004
	; ./sizes
	Plan 9 v4 63-bit file server
		sizeof(Dentry) = 124
		sizeof(Cache)  =  88

• added long(er) file name components (56 bytes), long enough for all but one
  name in my /.longnames file (68-byte .xml name).

• Fri Aug  6 21:43:41 PDT 2004
	; ./sizes
	Plan 9 v4 63-bit file server sizes
		sizeof(Dentry) = 160
		sizeof(Cache)  =  88

• touched up lib.h (from libc.h) to bring it up to date with formatting
  functions, verbs & flags.
• check now reports stack usage: 320 bytes upon entry to fsck first time,
  92 bytes of stack per recursion.  given 16000 bytes of stack,
  that's 170 recursions maximum.
• booted xtc (terminal) from fs64 (used fs64 as main file system)

note: current file server with triple-indirect blocks at 4k block size
	has a maximum file size of ~505GB (5.42×10ⁱⁱ).
	with quadruple-indirect blocks, max would be ~275TB @ 4k block size.

• got igbe fs driver working (a couple small changes)
• eliminated some gotos (started with 580, down to 454)
• added quadruple indirect blocks: lets us reach 2⁶⁳ with a 32kB block size
• got igbe boot driver & pxe booting working
• on-disk qid paths are now Offs, but 9p1 qids on the wire are still ulongs
• generalised & parameterised indirect block implementation
• tested with plain w0 fs, cached fake worm on w0, cw jukebox (hp 160fx)
• ip directories in fs & fs64 are identical except for whitespace and
  goto-elimination
• replaced most of nemo's ide code with newer ide code lifted from 9load,
  then from cpu kernel (sdata.c & support).  this brings us dma, rwm & lba48,
  finds ide controllers by itself, even pci ones, & copes with dead drives
  (i.e., doesn't panic).
• fixed long-standing bug that caused a 5-second delay before each console
  prompt on systems without a serial console.
• further type parameterisation: Userid (short), Timet (long), Devsize (vlong).
    Comment on v7 kernel portability work, quoting scj & dmr from BSTJ v57
    #6 part 2., p. 2038: ``The important data types used within the
    system were identified and specified using typedef: disk offsets,
    absolute times, internal device names, and the like.  This effort was
    carried out by K. Thompson.''
• corrected compat.h dependencies in mkfiles
• eliminated all warnings
• implemented truncation via wstat