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

[Ryan Harper <ryanh@us.ibm.com>]

* Alex Williamson <alex.williamson@hp.com> [2009-03-24 16:07]:
> 
> 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,

I've seen this as well, haven't had a chance to dig into the issue yet
either.  Certainly can test patches if anyone has an idea of what's
wrong here.

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
ryanh@us.ibm.com