Re: [PATCH] 1-2-3 GB

[Marvin Justice]

On Sunday 13 January 2002 02:24 pm, H. Peter Anvin wrote:
> By the way, expect user programs to fail due to lack of address space
> if you only give them 1 GB of userspace.  At 1 GB of userspace there
> is *no* address space which is compatible with the normal address
> space map available to the user process.

Actually, I think it will work for apps < `600MB since the mmap area is 
automatically adjusted to begin at PAGE_OFFSET/3.

cat /proc/1/maps

CONFIG_1GB
08048000-0804e000 r-xp 00000000 03:41 58716      /sbin/init
0804e000-08050000 rw-p 00005000 03:41 58716      /sbin/init
08050000-08054000 rwxp 00000000 00:00 0
40000000-40016000 r-xp 00000000 03:41 73822      /lib/ld-2.2.4.so
40016000-40017000 rw-p 00015000 03:41 73822      /lib/ld-2.2.4.so
40017000-40018000 rw-p 00000000 00:00 0
4002c000-4015e000 r-xp 00000000 03:41 73816      /lib/i686/libc-2.2.4.so
4015e000-40164000 rw-p 00131000 03:41 73816      /lib/i686/libc-2.2.4.so
40164000-40168000 rw-p 00000000 00:00 0
bfffe000-c0000000 rwxp fffff000 00:00 0

CONFIG_3GB
08048000-0804e000 r-xp 00000000 03:41 58716      /sbin/init
0804e000-08050000 rw-p 00005000 03:41 58716      /sbin/init
08050000-08054000 rwxp 00000000 00:00 0
15556000-1556c000 r-xp 00000000 03:41 73822      /lib/ld-2.2.4.so
1556c000-1556d000 rw-p 00015000 03:41 73822      /lib/ld-2.2.4.so
1556d000-1556e000 rw-p 00000000 00:00 0
15582000-156b4000 r-xp 00000000 03:41 73816      /lib/i686/libc-2.2.4.so
156b4000-156ba000 rw-p 00131000 03:41 73816      /lib/i686/libc-2.2.4.so
156ba000-156be000 rw-p 00000000 00:00 0
3fffe000-40000000 rwxp fffff000 00:00 0

Then again, I agree the 3GB option doesn't make much sense for 99.99% of 
cases.

-Marvin