On 2015/7/14 17:32, Jan Beulich wrote:
On 14.07.15 at 07:22, <tiejun.c...@intel.com> wrote:
+ for ( i = 0; i < memory_map.nr_map; i++ )
+ {
+ uint64_t end = e820[i].addr + e820[i].size;
Either loop index/boundary or used array are wrong here: In the
earlier loop you copied memory_map[0...nr_map-1] to
e820[n...n+nr_map-1], but here you're looping looking at
e820[0...nr_map-1]
You're right. I should lookup all e820[] like this,
for ( i = 0; i < nr; i++ )
Hmm, I would have thought you only care about either part of
the just glued together map.
+ if ( e820[i].type == E820_RAM &&
+ low_mem_end > e820[i].addr && low_mem_end < end )
Assuming you mean to look at the RDM e820[] entries here, this
is not a correct check: You don't care about partly or fully
contained, all you care about is whether low_mem_end extends
beyond the start of the region.
Here I'm looking at the e820 entry indicating low memory. Because
low_mem_end = hvm_info->low_mem_pgend << PAGE_SHIFT;
and when we allocate MMIO in pci.c, its possible to populate RAM so
hvm_info->low_mem_pgend would be changed over there. So we need to
compensate this loss with high memory. Here memory_map[] also records
the original low/high memory, so if low_mem_end is less-than the
original we need this compensation.
And I'm not disputing your intentions - I'm merely pointing out that
afaics the code above doesn't match these intentions. In particular
(as said) I don't see why you need to check low_mem_end < end.
Before we probably relocate RAM,
low_mem_end = hvm_info->low_mem_pgend << PAGE_SHIFT
and the e820 entry specific to low memory,
[e820[X].addr, end]
Here, end = e820[X].addr + e820[X].size;
Now low_mem_end = end.
After that, low_mem_end < end. so if
(low_mem_end > e820[X].addr && low_mem_end < end) is true, this means
that associated RAM entry is hitting, right? Then we need to revise this
entry as [e820[X].addr, low_mem_end], and compensate [end - low_mem_end]
to high memory. Anything I'm still wrong here?
Thanks
Tiejun
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