* Aurelien Jarno <aurel...@aurel32.net> [2010-12-25 16:37]: > On Wed, Dec 08, 2010 at 04:27:45PM -0200, Luiz Capitulino wrote: > > On Wed, 08 Dec 2010 12:23:12 -0600 > > Anthony Liguori <aligu...@linux.vnet.ibm.com> wrote: > > > > > On 12/08/2010 12:01 PM, Luiz Capitulino wrote: > > > > Currently, x86_64-softmmu qemu segfaults when trying to use> 4095M > > > > memsize. > > > > This patch adds a simple check and error message (much like the 2047 > > > > limit on > > > > 32-bit hosts) on ram_size in the control path after we determine we're > > > > not using kvm > > > > > > > > Upstream qemu-kvm is affected if using the -no-kvm option; this patch > > > > address > > > > the segfault there as well. > > > > > > > > Signed-off-by: Ryan Harper<ry...@us.ibm.com> > > > > Signed-off-by: Aurelien Jarno<aurel...@aurel32.net> > > > > --- > > > > NOTE: this patch was applied in the v0.12.x branch, but it seems it got > > > > lost for master > > > > > > > > > > No, it was intentional. We should fix the segv, this is not a known > > > limitation but rather a bug. > > > > A TCG bug, I presume? > > > > Do you have more details about this issue and how to reproduce it?
At the time of the bug, it was something simple like: qemu-system-x86_64 -m 4097 -hda /dev/null we'd get an imediate segfault. As you say, I'm not seeing it now on current git; I'll see about bisecting to see if we did get a fix for the issue. > > Support for more than 4GB of memory has been added a few years ago, > and I am not able to reproduce the problem anymore (I have booted a > 64-bit guest with 6GB of RAM, and make sure the guest use the whole > memory). I guess TCG itself is fine, but there might be a bug in > the MMU emulation in some cases. > > I also noticed that now i386-softmmu has been artificially limited to > 2047MB. Tthis configuration used to support up to 64GB of RAM (PAE) > on 64-bit hosts. > > -- > Aurelien Jarno GPG: 1024D/F1BCDB73 > aurel...@aurel32.net http://www.aurel33.net -- Ryan Harper Software Engineer; Linux Technology Center IBM Corp., Austin, Tx ry...@us.ibm.com
