64-bit capable block device layer

From: Rik van Riel (riel@conectiva.com.br)
Date: Wed Mar 07 2001 - 12:41:17 EST

Hi Linus,

how would you feel about having the block device layer 64-bit
capable, so Linux can have block devices of more than 2GB in
size ?

I know that 64-bit arithmetic is expensive on 32-bit platforms,
but I have the idea there is a way around that for people who
don't want 64-bit capable block devices.

1. use blkoff_t for all block number arithmetic

2. in some header file, have

#ifdef CONFIG_BLKDEV_64BIT
typedef long long blkoff_t
#else
typedef long blkoff_t
#endif

This way, people running smaller&slower machines can chose to
do the cheaper 32-bit arithmetic and only the people using huge
block devices will have to do the 64-bit arithmetic.

(yes, basically the same trick as we're using for PAE)

regards,

Rik 

--
Linux MM bugzilla: http://linux-mm.org/bugzilla.shtml

Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...

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This archive was generated by hypermail 2b29 : Wed Mar 07 2001 - 21:00:23 EST