Re: [Xen-devel] [Patch] Constrain DMADOM/swiotlb allocations to 1G phys to fix b44 NIC driver

[Keir Fraser <keir@xxxxxxxxxxxxx>]

How much should we care about Broadcom 4400? Wasn't it mainly used in old
notebooks?

 -- Keir

On 28/11/06 15:46, "Stephen C. Tweedie" <sct@xxxxxxxxxx> wrote:

> Hi all,
> 
> The b44 driver currently won't load on Xen kernels with 1G memory or
> more.  It tries to set a pci dma mask of 0x3ffffff (ie. it can only
> address 1G physical memory), but the swiotlb cannot deal with this ---
> swiotlb memory is allocated from the hypervisor's DMADOM heap, which is
> restricted to the bottom 2GB of physical memory.  So the pci dma mask
> cannot be set and the driver load fails with
> 
>         b44 0000:03:00.0: No usable DMA configuration, aborting.
> 
> It turns out that this 2GB / 31-bit constraint is magically hardcoded in
> a couple of places rather than being read correctly from config.h.  So
> this patch fixes that; changes config.h to specify a 1GB / 30-bit
> constraint for the DMADOM heap; and changes the x86/x86_64 swiotlb to
> request a 30-bit constraint for allocations of the swiotlb memory.
> 
> With this in place, b44 works.  (Red Hat bugzilla #208242).
> 
> --Stephen
> 
> # HG changeset patch
> # User Stephen Tweedie <sct@xxxxxxxxxx>
> # Date 1164722972 0
> # Node ID 6cbddc31f52d0bad2aa4b13452a4092dfeada47f
> # Parent  0af1ba62a14b4eaf1c0687d855edc7307edb21ba
> Clean up the DMADOM physical upper limit handling to properly honour
> settings in config.h.
> 
> Set the upper limit for DMADOM and swiotlb allocations to be 30 bits
> (1G) instead of 31 bits, to allow the b44 NIC driver to work.
> 
> Signed-off-by: Stephen Tweedie <sct@xxxxxxxxxx>
> 
> diff -r 0af1ba62a14b -r 6cbddc31f52d
> linux-2.6-xen-sparse/arch/i386/kernel/swiotlb.c
> --- a/linux-2.6-xen-sparse/arch/i386/kernel/swiotlb.c Tue Nov 28 11:47:28 2006
> +0000
> +++ b/linux-2.6-xen-sparse/arch/i386/kernel/swiotlb.c Tue Nov 28 14:09:32 2006
> +0000
> @@ -47,8 +47,8 @@ EXPORT_SYMBOL(swiotlb);
>   */
>  #define IO_TLB_SHIFT 11
>  
> -/* Width of DMA addresses in the IO TLB. 31 bits is an aacraid limitation. */
> -#define IO_TLB_DMA_BITS 31
> +/* Width of DMA addresses in the IO TLB. 30 bits is a b44 limitation. */
> +#define IO_TLB_DMA_BITS 30
>  
>  static int swiotlb_force;
>  static char *iotlb_virt_start;
> diff -r 0af1ba62a14b -r 6cbddc31f52d xen/common/memory.c
> --- a/xen/common/memory.c Tue Nov 28 11:47:28 2006 +0000
> +++ b/xen/common/memory.c Tue Nov 28 14:09:32 2006 +0000
> @@ -328,7 +328,7 @@ static long memory_exchange(XEN_GUEST_HA
>           (exch.out.address_bits <
>            (get_order_from_pages(max_page) + PAGE_SHIFT)) )
>      {
> -        if ( exch.out.address_bits < 31 )
> +        if ( exch.out.address_bits < MAX_DMADOM_BITS )
>          {
>              rc = -ENOMEM;
>              goto fail_early;
> @@ -541,7 +541,7 @@ long do_memory_op(unsigned long cmd, XEN
>               (reservation.address_bits <
>                (get_order_from_pages(max_page) + PAGE_SHIFT)) )
>          {
> -            if ( reservation.address_bits < 31 )
> +            if ( reservation.address_bits < MAX_DMADOM_BITS )
>                  return start_extent;
>              args.memflags = MEMF_dma;
>          }
> diff -r 0af1ba62a14b -r 6cbddc31f52d xen/include/asm-ia64/config.h
> --- a/xen/include/asm-ia64/config.h Tue Nov 28 11:47:28 2006 +0000
> +++ b/xen/include/asm-ia64/config.h Tue Nov 28 14:09:32 2006 +0000
> @@ -41,7 +41,9 @@
>  #define CONFIG_IOSAPIC
>  #define supervisor_mode_kernel (0)
>  
> -#define MAX_DMADOM_PFN (0x7FFFFFFFUL >> PAGE_SHIFT) /* 31 addressable bits */
> +#define MAX_DMADOM_BITS 30
> +#define MAX_DMADOM_MASK ((1UL << MAX_DMADOM_BITS) - 1)
> +#define MAX_DMADOM_PFN  (MAX_DMADOM_MASK >> PAGE_SHIFT)
>  
>  /* If PERFC is used, include privop maps.  */
>  #ifdef PERF_COUNTERS
> diff -r 0af1ba62a14b -r 6cbddc31f52d xen/include/asm-x86/config.h
> --- a/xen/include/asm-x86/config.h Tue Nov 28 11:47:28 2006 +0000
> +++ b/xen/include/asm-x86/config.h Tue Nov 28 14:09:32 2006 +0000
> @@ -82,7 +82,9 @@
>  /* Debug stack is restricted to 8kB by guard pages. */
>  #define DEBUG_STACK_SIZE 8192
>  
> -#define MAX_DMADOM_PFN 0x7FFFFUL /* 31 addressable bits */
> +#define MAX_DMADOM_BITS 30
> +#define MAX_DMADOM_MASK ((1UL << MAX_DMADOM_BITS) - 1)
> +#define MAX_DMADOM_PFN  (MAX_DMADOM_MASK >> PAGE_SHIFT)
>  
>  #ifndef __ASSEMBLY__
>  extern unsigned long _end; /* standard ELF symbol */
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