On Wed, Jan 09, 2013 at 09:43:05PM +0100, Thierry Reding wrote: > The I/O map cache is used to map large regions of physical memory in > smaller chunks to avoid running out of vmalloc()/ioremap() space. > > Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx> We already have a means where we record the mappings which ioremap() creates. If you look at /proc/vmallocinfo, you'll notice lines such as: 0xf7b72000-0xf7b74000 8192 e1000_probe+0x291/0xa68 [e1000e] phys=fc025000 ioremap which gives you the virtual address range, physical address and type of the mapping. Why do we need a duplicated data structure? Moreover, you seem to suggest that you want to break up a large ioremap() mapping into several smaller mappings. Why? The idea behind ioremap() is that this relationship holds true: ptr = ioremap(cookie + n, size); For any 'n' in the range 0 .. size, the location shall be accessible via ptr + n when using the IO space accessors. If you're going to break up a mapping into several smaller ones, this no longer holds true. If the problem is that you're ioremapping huge address ranges because you're passing larger-than-required resources to devices, then that's part of the problem too. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
