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SubjectRe: [PATCH] ramdisk for unusable memory > 960MB / > 2 GB
On Mon, 1 Feb 1999, Manfred Spraul wrote:

>This patch adds:
>- 2 new kernel functions (alloc_hugemem, free_hugemem) that manage
>physical, unmapped memory. (Note: if you have 1 GB memory, then there is
>usually 64 MB unused memory).
>- a special ramdisk that uses this memory. ( MAJOR=126, MINOR=0..7)

The idea is nice, but the help is fuzzy:

>+Hugeram Ramdisk
>+CONFIG_BLK_DEV_HUGERAMD
>+ Saying Y here makes it possible to use the memory above 1 gigabyte
>+ as a ramdisk. This only works if you have enabled CONFIG_HUGEMEM.

>+Huge memory support
>+CONFIG_HUGEMEM
>+ Enables kernel support for more than 2 gigabyte physical memory.
>+ Note that this memory is only used for special devices such as
>+ hugeramd.
>+
>+ If unsure, say 'N'.
>+

What about this:

----------------------------------------------------------------
Huge memory support
CONFIG_HUGEMEM
Enables kernel support for really huge amounts of RAM (beyond 1 Gigabyte)
Linux currently supports up to almost 1 Gigabyte of RAM (960MB to be exact)
on Intel and compatibles computers.
If this is too little for you, there are two things you can do:

1: Increase manually the limit to 1984MB.
Read the note in include/linux/page.h to do this.
2: Use the RAM above the 960MB limit (or above 1984MB if you applied 1:)
as a special ramdisk.

Saying Y here makes it possible to use the solution 2:
use the RAM above the limit as a ramdisk.

Note that to actually enable this ramdisk, you must also say Y to the
"Huge Ramdisk support" below.

----------------------------------------------------------------
Huge Ramdisk support
CONFIG_BLK_DEV_HUGERAMD
Saying Y here makes it possible to use the memory above 1 Gigabyte
as a ramdisk. This only works if you have enabled "Huge Memory support".

The ramdisk can be accessed through block special files
/dev/hugeram0 ... /dev/hugeram7, with major number 126 and
minor numbers 0..7 (do "man mknod" for help how to create them)

----------------------------------------------------------------

Also, the note in linux/include/asm-i386/page.h was fixed
(0x7000000 -> 0x80000000) in 2.2.1 so everything should be fine.

Massimiliano Ghilardi

----------------------------------------------------------------
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| Most have never had an experience. |
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