From: FUJITA Tomonori Previously, during initialization of the IOMMU tables, the last entry at each 4GB boundary is marked as used since there are many adapters which cannot handle DMAing across any 4GB boundary. The IOMMU doesn't allocate a memory area spanning LLD's segment boundary anymore. The segment boundary of devices are set to 4GB by default. So we can remove 4GB boundary protection now. Signed-off-by: FUJITA Tomonori Cc: Jeff Garzik Cc: James Bottomley Cc: Jens Axboe Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: Andrew Morton --- arch/powerpc/kernel/iommu.c | 21 +-------------------- 1 file changed, 1 insertion(+), 20 deletions(-) diff -puN arch/powerpc/kernel/iommu.c~iommu-sg-powerpc-remove-dma-4gb-boundary-protection arch/powerpc/kernel/iommu.c --- a/arch/powerpc/kernel/iommu.c~iommu-sg-powerpc-remove-dma-4gb-boundary-protection +++ a/arch/powerpc/kernel/iommu.c @@ -448,9 +448,6 @@ void iommu_unmap_sg(struct iommu_table * struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid) { unsigned long sz; - unsigned long start_index, end_index; - unsigned long entries_per_4g; - unsigned long index; static int welcomed = 0; struct page *page; @@ -472,6 +469,7 @@ struct iommu_table *iommu_init_table(str #ifdef CONFIG_CRASH_DUMP if (ppc_md.tce_get) { + unsigned long index; unsigned long tceval; unsigned long tcecount = 0; @@ -502,23 +500,6 @@ struct iommu_table *iommu_init_table(str ppc_md.tce_free(tbl, tbl->it_offset, tbl->it_size); #endif - /* - * DMA cannot cross 4 GB boundary. Mark last entry of each 4 - * GB chunk as reserved. - */ - if (protect4gb) { - entries_per_4g = 0x100000000l >> IOMMU_PAGE_SHIFT; - - /* Mark the last bit before a 4GB boundary as used */ - start_index = tbl->it_offset | (entries_per_4g - 1); - start_index -= tbl->it_offset; - - end_index = tbl->it_size; - - for (index = start_index; index < end_index - 1; index += entries_per_4g) - __set_bit(index, tbl->it_map); - } - if (!welcomed) { printk(KERN_INFO "IOMMU table initialized, virtual merging %s\n", novmerge ? "disabled" : "enabled"); _