Re: LZMA inclusion

["Jörn Engel" <joern@logfs.org>]

On Sun, 7 December 2008 23:32:32 +0000, Phillip Lougher wrote:
> 
> Currently, as mentioned above, Squashfs decompresses into a single 
> contiguous output buffer.  But, due to the linux kernel mailing list's 
> dislike of vmalloc, this is being changed.

Don't blame lkml, blame Intel and IBM.  Back in the days of the 386, a
beefy machine had 8MB of physical memory and 4GB of virtual memory
space.  Noone had to worry about fragmentation anymore.  If you needed a
1MB buffer, you'd just round up some 256 pages and instruct the mmu to
map them into a large contiguous address range in the virtual address
space.  Life was good indeed.

But physical memory has constantly grown since, while the virtual memory
space has for a long time stagnated.  Intel even introduced some
hardware hacks to use up to 64GB of physical memory with a measly 4GB of
virtual memory.  Now it was _virtual_ memory fragmentation that you had
to worry about.

These days most CPUs you'd buy are 64bit, so virtual memory space has
become useful again.  But as a kernel hacker, you have little control
over what hardware everyone is using.  And those weird systems with
more physical than virtual memory are still around. :(

Jörn

-- 
Don't patch bad code, rewrite it.
-- Kernigham and Pike, according to Rusty