1. 15 Nov, 2005 2 commits
    • Andi Kleen's avatar
      [PATCH] x86_64: Add 4GB DMA32 zone · a2f1b424
      Andi Kleen authored
      Add a new 4GB GFP_DMA32 zone between the GFP_DMA and GFP_NORMAL zones.
      
      As a bit of historical background: when the x86-64 port
      was originally designed we had some discussion if we should
      use a 16MB DMA zone like i386 or a 4GB DMA zone like IA64 or
      both. Both was ruled out at this point because it was in early
      2.4 when VM is still quite shakey and had bad troubles even
      dealing with one DMA zone.  We settled on the 16MB DMA zone mainly
      because we worried about older soundcards and the floppy.
      
      But this has always caused problems since then because
      device drivers had trouble getting enough DMA able memory. These days
      the VM works much better and the wide use of NUMA has proven
      it can deal with many zones successfully.
      
      So this patch adds both zones.
      
      This helps drivers who need a lot of memory below 4GB because
      their hardware is not accessing more (graphic drivers - proprietary
      and free ones, video frame buffer drivers, sound drivers etc.).
      Previously they could only use IOMMU+16MB GFP_DMA, which
      was not enough memory.
      
      Another common problem is that hardware who has full memory
      addressing for >4GB misses it for some control structures in memory
      (like transmit rings or other metadata).  They tended to allocate memory
      in the 16MB GFP_DMA or the IOMMU/swiotlb then using pci_alloc_consistent,
      but that can tie up a lot of precious 16MB GFPDMA/IOMMU/swiotlb memory
      (even on AMD systems the IOMMU tends to be quite small) especially if you have
      many devices.  With the new zone pci_alloc_consistent can just put
      this stuff into memory below 4GB which works better.
      
      One argument was still if the zone should be 4GB or 2GB. The main
      motivation for 2GB would be an unnamed not so unpopular hardware
      raid controller (mostly found in older machines from a particular four letter
      company) who has a strange 2GB restriction in firmware. But
      that one works ok with swiotlb/IOMMU anyways, so it doesn't really
      need GFP_DMA32. I chose 4GB to be compatible with IA64 and because
      it seems to be the most common restriction.
      
      The new zone is so far added only for x86-64.
      
      For other architectures who don't set up this
      new zone nothing changes. Architectures can set a compatibility
      define in Kconfig CONFIG_DMA_IS_DMA32 that will define GFP_DMA32
      as GFP_DMA. Otherwise it's a nop because on 32bit architectures
      it's normally not needed because GFP_NORMAL (=0) is DMA able
      enough.
      
      One problem is still that GFP_DMA means different things on different
      architectures. e.g. some drivers used to have #ifdef ia64  use GFP_DMA
      (trusting it to be 4GB) #elif __x86_64__ (use other hacks like
      the swiotlb because 16MB is not enough) ... . This was quite
      ugly and is now obsolete.
      
      These should be now converted to use GFP_DMA32 unconditionally. I haven't done
      this yet. Or best only use pci_alloc_consistent/dma_alloc_coherent
      which will use GFP_DMA32 transparently.
      Signed-off-by: default avatarAndi Kleen <ak@suse.de>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      a2f1b424
    • Andi Kleen's avatar
      [PATCH] x86_64: Update defconfig · 56720367
      Andi Kleen authored
      Rerun and enable autofs 4, relayfs and softdog
      Signed-off-by: default avatarAndi Kleen <ak@suse.de>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      56720367
  2. 05 Nov, 2005 6 commits
  3. 04 Nov, 2005 31 commits
  4. 03 Nov, 2005 1 commit