Swap on video ram

From ArchWiki
Revision as of 21:22, 6 October 2007 by Stonecrest (Talk | contribs) (cleanup)

Jump to: navigation, search

Tango-document-new.pngThis article is a stub.Tango-document-new.png

Notes: please use the first argument of the template to provide more detailed indications. (Discuss in Talk:Swap on video ram#)

This is a work in progress

The fast memory on your graphics card (if you have one) can be used as general ram by using the MTD subsystem of the kernel. At the moment that part is not included in the stock arch kernel, so you have to build your own kernel. Using ABS is probably the easiest way.

How To

Kernel Stuff

You can rebuild the whole kernel as shown here. The modules can probably be built separately though (perhaps with a pkgbuild)

  1. Get the ABS tree
  2. copy the /var/abs/kernels/kernel26 to /var/abs/local/kernel26-mtd, that will be your working directory
  3. change the name of the package to something else ie. from kernel26 to kernel26-mtd or something like that
  4. get and extract the sources with
    makepkg -o
  5. modify the configuration of the kernel, adding
    1. mtd_block (maybe mtd_char)
    2. mtd_slram
    3. mtd_phram (alternative and successor to slram)
    4. mtd_ram probably too.
    5. other settings that go with those choices:
CONFIG_MTD_MAP_BANK_WIDTH_1=y
CONFIG_MTD_MAP_BANK_WIDTH_2=y
CONFIG_MTD_MAP_BANK_WIDTH_4=y
# CONFIG_MTD_MAP_BANK_WIDTH_8 is not set
# CONFIG_MTD_MAP_BANK_WIDTH_16 is not set
# CONFIG_MTD_MAP_BANK_WIDTH_32 is not set
CONFIG_MTD_CFI_I1=y
CONFIG_MTD_CFI_I2=y

That's what the mtd section of my config ends up looking like. You can add this (almost?) anywhere in the config; just search for MTD, and replace the '#CONFIG_MTD= # is not set' with something else:

# Memory Technology Devices (MTD)
#
CONFIG_MTD=m
# CONFIG_MTD_DEBUG is not set
# CONFIG_MTD_CONCAT is not set
CONFIG_MTD_PARTITIONS=y
# CONFIG_MTD_REDBOOT_PARTS is not set

#
# User Modules And Translation Layers
#
CONFIG_MTD_CHAR=m
# CONFIG_MTD_BLKDEVS is not set
CONFIG_MTD_BLOCK=m # is not set
# CONFIG_MTD_BLOCK_RO is not set
# CONFIG_FTL is not set
# CONFIG_NFTL is not set
# CONFIG_INFTL is not set
# CONFIG_RFD_FTL is not set
# CONFIG_SSFDC is not set

#
# RAM/ROM/Flash chip drivers
#
# CONFIG_MTD_CFI is not set
# CONFIG_MTD_JEDECPROBE is not set
CONFIG_MTD_MAP_BANK_WIDTH_1=y
CONFIG_MTD_MAP_BANK_WIDTH_2=y
CONFIG_MTD_MAP_BANK_WIDTH_4=y
# CONFIG_MTD_MAP_BANK_WIDTH_8 is not set
# CONFIG_MTD_MAP_BANK_WIDTH_16 is not set
# CONFIG_MTD_MAP_BANK_WIDTH_32 is not set
CONFIG_MTD_CFI_I1=y
CONFIG_MTD_CFI_I2=y
# CONFIG_MTD_CFI_I4 is not set
# CONFIG_MTD_CFI_I8 is not set
CONFIG_MTD_RAM=m
# CONFIG_MTD_ROM is not set
# CONFIG_MTD_ABSENT is not set
# CONFIG_MTD_OBSOLETE_CHIPS is not set

#
# Mapping drivers for chip access
#
# CONFIG_MTD_COMPLEX_MAPPINGS is not set
# CONFIG_MTD_TS5500 is not set
CONFIG_MTD_PLATRAM=m

#
# Self-contained MTD device drivers
#
# CONFIG_MTD_PMC551 is not set
# CONFIG_MTD_DATAFLASH is not set
# CONFIG_MTD_M25P80 is not set
CONFIG_MTD_SLRAM=m
CONFIG_MTD_PHRAM=m
# CONFIG_MTD_MTDRAM is not set
# CONFIG_MTD_BLOCK2MTD is not set

#
# Disk-On-Chip Device Drivers
#
# CONFIG_MTD_DOC2000 is not set
# CONFIG_MTD_DOC2001 is not set
# CONFIG_MTD_DOC2001PLUS is not set

#
# NAND Flash Device Drivers
#
# CONFIG_MTD_NAND is not set

#
# OneNAND Flash Device Drivers
#
# CONFIG_MTD_ONENAND is not set

Post-Kernel Stuff

When you are running the new kernel with those modules built, you choose the pci address ranges where the device goes and then add something like the following to your rc.local:

# for using vram as swap
modprobe slram map=VRAM,0xSTART RANGE HERE,+0xGOING THIS MUCH FARTHER
modprobe mtdchar #probably unnecessary
modprobe mtdblock
mkswap /dev/mtdblock0
swapon /dev/mtdblock0 -p 10 #higher priority gets used before disk

you get the whole range you can take from lspci -vvv, looking for something that names your video card.

Learn hex arithmetic, or use a calculator (qalculate). You leave a certain space at the beginning of the address range, so that you graphics card can still function which is at least 4MiB if you decide to use the vga driver (at up to 1280x1024).

Example

lspci -vvv
01:00.0 VGA compatible controller: ATI Technologies Inc RV350 AR [Radeon 9600] (prog-if 00 [VGA])
	Subsystem: PC Partner Limited Unknown device 0830
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B-
	Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
	Latency: 64 (2000ns min), Cache Line Size: 32 bytes
	Interrupt: pin A routed to IRQ 11
''	Region 0: Memory at e0000000 (32-bit, prefetchable) [size=256M]''
	Region 1: I/O ports at c800 [size=256]
	Region 2: Memory at ff8f0000 (32-bit, non-prefetchable) [size=64K]
	Expansion ROM at ff8c0000 [disabled] [size=128K]
	Capabilities: [58] AGP version 2.0
		Status: RQ=80 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW+ AGP3- Rate=x1,x2,x4
		Command: RQ=32 ArqSz=0 Cal=0 SBA+ AGP+ GART64- 64bit- FW- Rate=x4
	Capabilities: [50] Power Management version 2
		Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 PME-Enable- DSel=0 DScale=0 PME-

So here I have an address range starting at 0xe0000000, with a size of 256MiB, aka +0x10000000.

So choose how much space you can spare; maybe it is 16MiB which is 0x01000000.

That space has to be at the start of the address range: add 0x01000000 to 0xe00000000 to get the start, and then subtract that from the end to make sure that you are using the whole space.

External Links

MTD website Gentoo Wiki