Can't boot guest with more than 3585MB when using large pages

Alex Williamson
2009-03-24T21:06:53Z

On a 2.6.29, x86_64 host/guest, what's special about specifying a guest
size of -m 3586 when using -mem-path backed by hugetlbfs? 3585 works,
3586 hangs here:

...
PCI-DMA: Using software bounce buffering for IO (SWIOTLB)
Placing 64MB software IO TLB between ffff880020000000 - ffff880024000000
software IO TLB at phys 0x20000000 - 0x24000000
Memory: 3504832k/4196352k available (2926k kernel code, 524740k absent, 166780k reserved, 1260k data, 496k init)

I can back -mem-path by tmpfs or disk and it works fine. Also works
with no -mem-path, but it would obviously be nice to benefit from large
pages on big guests. The system has plenty of huge pages to back the
request, and booting with -mem-prealloc makes no difference. Tested on
latest git as of today. Thanks,

Alex