[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Jan Kiszka]

Avi Kivity wrote:
> Zhang, Xiantao wrote:
>> Jes Sorensen wrote:
>>  
>>> Hi,
>>>
>>> The latest changes to qemu-kvm breaks miserably if one tries to build
>>> without CONFIG_GDBSTUB.
>>>
>>> Jes
>>>     
>>
>> --- qemu-kvm.orig/vl.c
>> +++ qemu-kvm/vl.c
>> @@ -4417,13 +4417,11 @@
>>          }
>>          if (cpu_can_run(env))
>>              ret = qemu_cpu_exec(env);
>> -#ifndef CONFIG_GDBSTUB
>> ^^^^^^^^^^^
>> Don't know why change #ifdef to #ifndef in upstream, and I remember it
>> should be ifdef before. I believe this stuff should be compiled only
>> if CONFIG_GDBSTUB is defined.    
> 
> This was introduced by
> 
> commit 704aec581c1683750e313832ba3aa4813d59cbd0
> Author: Xiantao Zhang <xiantao.zhang@intel.com>
> Date:   Thu Nov 27 17:23:27 2008 +0800
> 
>    Build fix for !CONFIG_GDBSTUB case
>      Once CONFIG_GDBSTUB not configured, compile will generate error
> 
> In upstream.  Please fix it in upstream and qemu-kvm.git will get the
> fix from there.

Given that CONFIG_GDBSTUB is always true upstream, I tend to say:
Finally drop it upstream and keep this (or a more arch-local) workaround
for missing ia64 gdbstub support downstream.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Avi Kivity]

Jan Kiszka wrote:
>> In upstream.  Please fix it in upstream and qemu-kvm.git will get the
>> fix from there.
>>     
>
> Given that CONFIG_GDBSTUB is always true upstream, I tend to say:
> Finally drop it upstream and keep this (or a more arch-local) workaround
> for missing ia64 gdbstub support downstream.
>   

I agree, unless

- we want to make gdbstub support configurable (don't see any 
overwhelming reason for this, but maybe others do)
- we want to merge ia64 kvm support upstream, and don't want to impose 
gdbstub support (though I'd recommend properly implementing gdbstub)

In any case, I'm okay with dropping the check upstream and applying the 
local fixup.

-- 
error compiling committee.c: too many arguments to function

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Jan Kiszka]

Avi Kivity wrote:
> Jan Kiszka wrote:
>>> In upstream.  Please fix it in upstream and qemu-kvm.git will get the
>>> fix from there.
>>>     
>>
>> Given that CONFIG_GDBSTUB is always true upstream, I tend to say:
>> Finally drop it upstream and keep this (or a more arch-local) workaround
>> for missing ia64 gdbstub support downstream.
>>   
> 
> I agree, unless
> 
> - we want to make gdbstub support configurable (don't see any
> overwhelming reason for this, but maybe others do)
> - we want to merge ia64 kvm support upstream, and don't want to impose
> gdbstub support (though I'd recommend properly implementing gdbstub)
> 
> In any case, I'm okay with dropping the check upstream and applying the
> local fixup.

The last ia64 tcg patch I saw one or two days ago was missing gdb
support, too (and may suffer from some brokenness for that reason). But
I would suggest for both cases (tcg and kvm) to temporarily provide
stubs/placeholders instead of keeping the central #ifdefs.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Avi Kivity]

Jan Kiszka wrote:
>> I agree, unless
>>
>> - we want to make gdbstub support configurable (don't see any
>> overwhelming reason for this, but maybe others do)
>> - we want to merge ia64 kvm support upstream, and don't want to impose
>> gdbstub support (though I'd recommend properly implementing gdbstub)
>>
>> In any case, I'm okay with dropping the check upstream and applying the
>> local fixup.
>>     
>
> The last ia64 tcg patch I saw one or two days ago was missing gdb
> support, too (and may suffer from some brokenness for that reason).

I didn't see ia64/tcg.  Did you mean s390?  That was host only IIRC.

>  But
> I would suggest for both cases (tcg and kvm) to temporarily provide
> stubs/placeholders instead of keeping the central #ifdefs.
>   

Agreed.

-- 
error compiling committee.c: too many arguments to function

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Jan Kiszka]

Avi Kivity wrote:
> Jan Kiszka wrote:
>>> I agree, unless
>>>
>>> - we want to make gdbstub support configurable (don't see any
>>> overwhelming reason for this, but maybe others do)
>>> - we want to merge ia64 kvm support upstream, and don't want to impose
>>> gdbstub support (though I'd recommend properly implementing gdbstub)
>>>
>>> In any case, I'm okay with dropping the check upstream and applying the
>>> local fixup.
>>>     
>>
>> The last ia64 tcg patch I saw one or two days ago was missing gdb
>> support, too (and may suffer from some brokenness for that reason).
> 
> I didn't see ia64/tcg.  Did you mean s390?  That was host only IIRC.

Ah, you are right.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Jes Sorensen]

[-- Attachment #1: Type: text/plain, Size: 736 bytes --]

Avi Kivity wrote:
> I agree, unless
> 
> - we want to make gdbstub support configurable (don't see any 
> overwhelming reason for this, but maybe others do)
> - we want to merge ia64 kvm support upstream, and don't want to impose 
> gdbstub support (though I'd recommend properly implementing gdbstub)
> 
> In any case, I'm okay with dropping the check upstream and applying the 
> local fixup.

Hi,

Here's a patch that fixes the #ifndef to make it the #ifdef as it was
intended.

I am quite fine with us trying to drop all the #ifdefs and introduce
noop wrappers for archs that do not provide the gdbstubs (ie. ia64), but
to start with we better just fix the #ifndef to make it behave like it
was originally intended.

Cheers,
Jes




[-- Attachment #2: 0001-qemu-kdbstub.patch --]
[-- Type: text/x-patch, Size: 560 bytes --]

Fix incorrect #ifndef for CONFIG_GETSTUB, which should have been an
#ifdef.

Signed-off-by: Jes Sorensen <jes@sgi.com>

---
 vl.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: qemu/vl.c
===================================================================
--- qemu.orig/vl.c
+++ qemu/vl.c
@@ -4350,7 +4350,7 @@
         }
         if (cpu_can_run(env))
             ret = qemu_cpu_exec(env);
-#ifndef CONFIG_GDBSTUB
+#ifdef CONFIG_GDBSTUB
         if (ret == EXCP_DEBUG) {
             gdb_set_stop_cpu(env);
             debug_requested = 1;

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Jan Kiszka]

Jes Sorensen wrote:
> Avi Kivity wrote:
>> I agree, unless
>>
>> - we want to make gdbstub support configurable (don't see any
>> overwhelming reason for this, but maybe others do)
>> - we want to merge ia64 kvm support upstream, and don't want to impose
>> gdbstub support (though I'd recommend properly implementing gdbstub)
>>
>> In any case, I'm okay with dropping the check upstream and applying
>> the local fixup.
> 
> Hi,
> 
> Here's a patch that fixes the #ifndef to make it the #ifdef as it was
> intended.
> 
> I am quite fine with us trying to drop all the #ifdefs and introduce
> noop wrappers for archs that do not provide the gdbstubs (ie. ia64), but
> to start with we better just fix the #ifndef to make it behave like it
> was originally intended.

As the original change this patch (correctly) fixes broke gdbstub
support in qemu-kvm for all archs + it is still a deviation from
upstream, please take the chance and go for ia64 stubs.

BTW, I'm planning to submit a cleanup patch for CONFIG_GDBSTUB to
upstream soon.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Jes Sorensen]

Jan Kiszka wrote:
> As the original change this patch (correctly) fixes broke gdbstub
> support in qemu-kvm for all archs + it is still a deviation from
> upstream, please take the chance and go for ia64 stubs.

Jan,

There's far more to do in upstream than just gdbstubs for ia64 to be
usable :-(

We'll get to gdbstubs at some point, but there's too many other higher
priority items to deal with first.

Cheers,
Jes

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Jan Kiszka]

Jes Sorensen wrote:
> Jan Kiszka wrote:
>> As the original change this patch (correctly) fixes broke gdbstub
>> support in qemu-kvm for all archs + it is still a deviation from
>> upstream, please take the chance and go for ia64 stubs.
> 
> Jan,
> 
> There's far more to do in upstream than just gdbstubs for ia64 to be
> usable :-(
> 
> We'll get to gdbstubs at some point, but there's too many other higher
> priority items to deal with first.

I'm not asking for full gdbstub support at this point, just for a build
workaround at arch-level (or in arch-specific blocks, in gdbstub.c e.g.)
instead of patching generic code with global risk of regressions.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

[Qemu-devel] Re: [patch] fix qemu-kvm to build when gdbstub is disabled

[Jes Sorensen]

Jan Kiszka wrote:
> I'm not asking for full gdbstub support at this point, just for a build
> workaround at arch-level (or in arch-specific blocks, in gdbstub.c e.g.)
> instead of patching generic code with global risk of regressions.

Oh, I see.

I already submitted that to Avi, making gdb_set_stop_cpu() a noop on
ia64. Since there's no target-ia64/ directory in mainline qemu.git yet,
that fix will have to live in qemu-kvm for the time being.

I am fine if you wish to remove all the #ifdef CONFIG_GDBSTUB bits.

Cheers,
Jes