On 2015/6/16 17:40, Jan Beulich wrote:
On 16.06.15 at 11:29, <tiejun.c...@intel.com> wrote:
I'm trying to walk into this direction:
/*
* We'll skip all space overlapping with reserved memory later,
* so we need to increase mmio_total to compensate them.
*/
for ( j = 0; j < memory_map.nr_map ; j++ )
{
uint64_t conflict_size = 0;
if ( memory_map.map[j].type != E820_RAM )
{
reserved_start = memory_map.map[j].addr;
reserved_size = memory_map.map[j].size;
reserved_end = reserved_start + reserved_size;
if ( check_overlap(pci_mem_start, pci_mem_end - pci_mem_start,
reserved_start, reserved_size) )
{
/*
* Calculate how much mmio range conflict with
* reserved device memory.
*/
conflict_size += reserved_size;
/*
* But we may need to subtract those sizes beyond the
* pci memory, [pci_mem_start, pci_mem_end].
*/
if ( reserved_start < pci_mem_start )
conflict_size -= (pci_mem_start - reserved_start);
if ( reserved_end > pci_mem_end )
conflict_size -= (reserved_end - pci_mem_end);
}
}
if ( conflict_size )
{
uint64_t conflict_size = max_t(
uint64_t, conflict_size, max_bar_sz);
conflict_size &= ~(conflict_size - 1);
mmio_total += conflict_size;
}
}
This last thing goes in the right direction, but is complete overkill
when you have a small reserved region and a huge BAR. You
Yeah, this may waste some spaces in this worst case but I this think
this can guarantee our change don't impact on the original expectation,
right?
ought to work out the smallest power-of-2 region enclosing the
Okay. I remember the smallest size of a given PCI I/O space is 8 bytes,
and the smallest size of a PCI memory space is 16 bytes. So
/* At least 16 bytes to align a PCI BAR size. */
uint64_t align = 16;
reserved_start = memory_map.map[j].addr;
reserved_size = memory_map.map[j].size;
reserved_start = (reserved_star + align) & ~(align - 1);
reserved_size = (reserved_size + align) & ~(align - 1);
Is this correct?
reserved range (albeit there are tricky corner cases to consider).
Yeah, its a little tricky since RMRR always owns a fixed start address,
so we can't reorder them with all pci bars. I just think at least we
should provide a correct solution now, then further look into what can
be optimized. So I think we'd better get conflict_size with
max(conflict_size, max_bar_sz), right?
Thanks
Tiejun
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
