Re: [Qemu-devel] Re: [PATCH] Fix segfault with ram_size > 4095M without kvm
On Wed, Jan 05, 2011 at 01:04:51PM -0600, Ryan Harper wrote: > * Ryan Harper [2011-01-04 09:49]: > > * Aurelien Jarno [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 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 > > > > > > Signed-off-by: Aurelien Jarno > > > > > > --- > > > > > > 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. > > I attempted to bisect, but there a couple commits around where the issue > was fixed that broke git bisect =( That narrowed it down to about 5 > commits to check. > > This the last git commit where I can reproduce the segfault with the > above test case (qemu invocation). > > commit 0aef4261ac0ec9089ade0e3a92f986cb4ba7317e > Author: Aurelien Jarno > Date: Thu Mar 11 21:29:42 2010 +0100 > > target-ppc: fix evsrwu and evsrws (second try) > > Signed-off-by: Aurelien Jarno > > > The next 4 commits don't compile so they are untest-able: > > commit 14f24e1465edc44b9b4d89fbbea66e06088154e1 > - fails to build with: > - ./configure --target-list=x86_64-softmmu && make clean && make > /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': > /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported > TARGET_PHYS_ADDR_SPACE_BITS > /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': > /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported > TARGET_PHYS_ADDR_SPACE_BITS > make[1]: *** [exec.o] Error 1 > make: *** [subdir-x86_64-softmmu] Error 2 > > commit 7bc7b099dfa38a856b1bc892c0f9f3d6fe28e170 > - fails to build with: > - ./configure --target-list=x86_64-softmmu && make clean && make > /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': > /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported > TARGET_PHYS_ADDR_SPACE_BITS > /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': > /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported > TARGET_PHYS_ADDR_SPACE_BITS > make[1]: *** [exec.o] Error 1 > make: *** [subdir-x86_64-softmmu] Error 2 > > commit b9f83121a13153536d886305414b540460c34508 > - fails to build with: > - ./configure --target-list=x86_64-softmmu && make clean && make > /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': > /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported > TARGET_PHYS_ADDR_SPACE_BITS > /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': > /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported > TARGET_PHYS_ADDR_SPACE_BITS > make[1]: *** [exec.o] Error 1 > make: *** [subdir-x86_64-softmmu] Error 2 > > commit 5270589032f450ae7c3448730855aa18ff68ccff > - fails to build with: > - ./configure --target-list=x86_64-softmmu && make clean && make > /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': > /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported > TARGET_PHYS_ADDR_SPACE_BITS > /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': > /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported > TARGET_PHYS_ADDR_SPACE_BITS > make[1]: *** [exec.o] Error 1 > make: *** [subdir-x86_64-softmmu] Error 2 > > > And this commit compiles and the test case no longer segfaults. So I'd > say things are fixed at this point. > > commit 5cd2c5b6ad75c46d40118ac67c0c09d4e7930a65 > - compiles and issue is no longer present. > - ./configure --target-list=x86_64-softmmu && make clean && make && > sudo x86_64-softmmu/qemu-syem-x86_64 -L pc-bios -hda /dev/null -m 4097 > It's more likely this commit which fixes the bug. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurel...@aurel32.net
Re: [Qemu-devel] Re: [PATCH] Fix segfault with ram_size > 4095M without kvm
* Ryan Harper [2011-01-04 09:49]: > * Aurelien Jarno [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 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 > > > > > Signed-off-by: Aurelien Jarno > > > > > --- > > > > > 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. I attempted to bisect, but there a couple commits around where the issue was fixed that broke git bisect =( That narrowed it down to about 5 commits to check. This the last git commit where I can reproduce the segfault with the above test case (qemu invocation). commit 0aef4261ac0ec9089ade0e3a92f986cb4ba7317e Author: Aurelien Jarno Date: Thu Mar 11 21:29:42 2010 +0100 target-ppc: fix evsrwu and evsrws (second try) Signed-off-by: Aurelien Jarno The next 4 commits don't compile so they are untest-able: commit 14f24e1465edc44b9b4d89fbbea66e06088154e1 - fails to build with: - ./configure --target-list=x86_64-softmmu && make clean && make /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS make[1]: *** [exec.o] Error 1 make: *** [subdir-x86_64-softmmu] Error 2 commit 7bc7b099dfa38a856b1bc892c0f9f3d6fe28e170 - fails to build with: - ./configure --target-list=x86_64-softmmu && make clean && make /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS make[1]: *** [exec.o] Error 1 make: *** [subdir-x86_64-softmmu] Error 2 commit b9f83121a13153536d886305414b540460c34508 - fails to build with: - ./configure --target-list=x86_64-softmmu && make clean && make /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS make[1]: *** [exec.o] Error 1 make: *** [subdir-x86_64-softmmu] Error 2 commit 5270589032f450ae7c3448730855aa18ff68ccff - fails to build with: - ./configure --target-list=x86_64-softmmu && make clean && make /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS make[1]: *** [exec.o] Error 1 make: *** [subdir-x86_64-softmmu] Error 2 And this commit compiles and the test case no longer segfaults. So I'd say things are fixed at this point. commit 5cd2c5b6ad75c46d40118ac67c0c09d4e7930a65 - compiles and issue is no longer present. - ./configure --target-list=x86_64-softmmu && make clean && make && sudo x86_64-softmmu/qemu-syem-x86_64 -L pc-bios -hda /dev/null -m 4097 -- Ryan Harper Software Engineer; Linux Technology Center IBM Corp., Austin, Tx ry...@us.ibm.com
Re: [Qemu-devel] Re: [PATCH] Fix segfault with ram_size > 4095M without kvm
* Aurelien Jarno [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 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 > > > > Signed-off-by: Aurelien Jarno > > > > --- > > > > 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
[Qemu-devel] Re: [PATCH] Fix segfault with ram_size > 4095M without kvm
On Wed, Dec 08, 2010 at 04:27:45PM -0200, Luiz Capitulino wrote: > On Wed, 08 Dec 2010 12:23:12 -0600 > Anthony Liguori 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 > > > Signed-off-by: Aurelien Jarno > > > --- > > > 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? 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
[Qemu-devel] Re: [PATCH] Fix segfault with ram_size > 4095M without kvm
On 12/08/2010 12:27 PM, Luiz Capitulino wrote:
On Wed, 08 Dec 2010 12:23:12 -0600
Anthony Liguori 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
Signed-off-by: Aurelien Jarno
---
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?
Dunno, that's why we shouldn't just paper over it.
Regards,
Anthony Liguori
Regards,
Anthony Liguori
vl.c |6 ++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/vl.c b/vl.c
index 2dbb6db..bb9c21c 100644
--- a/vl.c
+++ b/vl.c
@@ -5792,6 +5792,12 @@ int main(int argc, char **argv, char **envp)
fprintf(stderr, "failed to initialize KVM\n");
exit(1);
}
+} else {
+/* without kvm enabled, we can only support 4095 MB RAM */
+if (ram_size> (4095UL<< 20)) {
+fprintf(stderr, "qemu: without kvm support at most 4095 MB RAM can be
simulated\n");
+exit(1);
+}
}
if (qemu_init_main_loop()) {
[Qemu-devel] Re: [PATCH] Fix segfault with ram_size > 4095M without kvm
On Wed, 08 Dec 2010 12:23:12 -0600
Anthony Liguori 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
> > Signed-off-by: Aurelien Jarno
> > ---
> > 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?
>
> Regards,
>
> Anthony Liguori
>
> > vl.c |6 ++
> > 1 files changed, 6 insertions(+), 0 deletions(-)
> >
> > diff --git a/vl.c b/vl.c
> > index 2dbb6db..bb9c21c 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -5792,6 +5792,12 @@ int main(int argc, char **argv, char **envp)
> > fprintf(stderr, "failed to initialize KVM\n");
> > exit(1);
> > }
> > +} else {
> > +/* without kvm enabled, we can only support 4095 MB RAM */
> > +if (ram_size> (4095UL<< 20)) {
> > +fprintf(stderr, "qemu: without kvm support at most 4095 MB RAM
> > can be simulated\n");
> > +exit(1);
> > +}
> > }
> >
> > if (qemu_init_main_loop()) {
> >
>
[Qemu-devel] Re: [PATCH] Fix segfault with ram_size > 4095M without kvm
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
Signed-off-by: Aurelien Jarno
---
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.
Regards,
Anthony Liguori
vl.c |6 ++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/vl.c b/vl.c
index 2dbb6db..bb9c21c 100644
--- a/vl.c
+++ b/vl.c
@@ -5792,6 +5792,12 @@ int main(int argc, char **argv, char **envp)
fprintf(stderr, "failed to initialize KVM\n");
exit(1);
}
+} else {
+/* without kvm enabled, we can only support 4095 MB RAM */
+if (ram_size> (4095UL<< 20)) {
+fprintf(stderr, "qemu: without kvm support at most 4095 MB RAM can be
simulated\n");
+exit(1);
+}
}
if (qemu_init_main_loop()) {
