Adding some more gentlemen's. > -----Original Message----- > From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel- > owner@xxxxxxxxxxxxxxx] On Behalf Of Bhushan Bharat-R65777 > Sent: Thursday, May 31, 2012 4:34 PM > To: linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Cc: agraf@xxxxxxx > Subject: memblock_end_of_DRAM() return end address + 1 > > Hi All, > > memblock_end_of_DRAM() defined in mm/memblock.c returns base_address + size; So > this is not returning the end_of_DRAM, it is basically returning the end_of_DRAM > + 1. The name looks to suggest that this returns end address on DRAM. > > IIUC, it looks like that some code assumes this returns the end address while > some assumes this returns end address + 1. > > Example: > 1. arch/powerpc/platforms/85xx/mpc85xx_ds.c > > > <cut> > > #ifdef CONFIG_SWIOTLB > if (memblock_end_of_DRAM() > max) { > ppc_swiotlb_enable = 1; > set_pci_dma_ops(&swiotlb_dma_ops); > ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb; > } > #endif > > <cut> > <cut> > > > Where max = 0xffffffff; So we assumes that memblock_end_of_DRAM() actually > returns end address. > > ------ > 2. > > In arch/powerpc/kernel/dma.c > > > static int dma_direct_dma_supported(struct device *dev, u64 mask) { #ifdef > CONFIG_PPC64 > /* Could be improved so platforms can set the limit in case > * they have limited DMA windows > */ > return mask >= get_dma_offset(dev) + (memblock_end_of_DRAM() - 1); > > > <cut> > > It looks to that here we assume base + addr + 1; > > ----------- > > > Thanks > -Bharat > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the > body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href