Re: [ kvm-Bugs-1807620 ] KVM's --disable-gcc-check doesn't work

Anthony Liguori
2007-10-05T17:00:06Z

Gregory Haskins wrote:
> On Thu, 2007-10-04 at 18:33 +0200, Farkas Levente wrote:
>
>> hi,
>> what's the real reason that kvm can't be compiled gcc-4.x?
>> wouldn't it be better to be able to compile with the current compilers too?
>>
>
> Its actually an issue with QEMUs cpu emulation code. It takes advantage
> of compiler traits that are no longer true in the 4.x series. The code
> will actually compile under 4.x however. It just will not run properly.
> However, KVM doesn't use QEMUs cpu emulation, so if you do not care
> about running with KVM disabled (e.g. -no-kvm), you don't technically
> need to worry about it.
>

FWIW, there are patches that allow QEMU to compile and work with GCC 4
but, so far, certain folks in the QEMU community have objected strongly
to them (look for the threads about post-processing GCC assembly output).

Those patches do work with KVM (and -no-kvm still works). However, it
would be a bad idea to apply them to the KVM QEMU tree b/c it would make
merging in the future much more difficult.

Regards,

Anthony Liguori

> Hope that helps.
> -Greg
>
>
>> SourceForge.net wrote:
>>
>>> Bugs item #1807620, was opened at 2007-10-04 18:25
>>> Message generated for change (Tracker Item Submitted) made by Item Submitter
>>> You can respond by visiting:
>>> https://sourceforge.net/tracker/?func=detail&atid=893831&aid=1807620&group_id=180599
>>>
>>> Please note that this message will contain a full copy of the comment thread,
>>> including the initial issue submission, for this request,
>>> not just the latest update.
>>> Category: None
>>> Group: None
>>> Status: Open
>>> Resolution: None
>>> Priority: 5
>>> Private: No
>>> Submitted By: Technologov (technologov)
>>> Assigned to: Nobody/Anonymous (nobody)
>>> Summary: KVM's --disable-gcc-check doesn't work
>>>
>>> Initial Comment:
>>> KVM's configure switch: "--disable-gcc-check" doesn't work.
>>>
>>> This bug makes KVM very hard to compile on openSUSE 10.2/10.3, which, unlike Fedora doesn't have compat-gcc-34 package.
>>>
>>> Here is the error:
>>>
>>> alexey@suse103-home:~/Linstall/kvm-45> ./configure --disable-gcc-check
>>> ./configure: cannot locate gcc 3.x. please install it or specify with --qemu-cc
>>>
>>> According to HELP, it should work:
>>> alexey@suse103-home:~/Linstall/kvm-45> ./configure --help
>>> Usage: ./configure [options]
>>>
>>> Options include:
>>>
>>> --prefix=PREFIX where to install things (/usr/local)
>>> --with-patched-kernel don't use external module
>>> --kerneldir=DIR kernel build directory (/lib/modules/2.6.22.5-31-bigsmp/build)
>>> --qemu-cc="" compiler for qemu (needs gcc3.x) ()
>>> --disable-gcc-check don't insist on gcc-3.x
>>> - this will break running without kvm
>>>
>>>
>>> Host: openSUSE 10.3, 32-bit, Intel Core 2 CPU, KVM-45.
>>>
>>> -Alexey Technologov
>>>
>>> ----------------------------------------------------------------------
>>>
>>> You can respond by visiting:
>>> https://sourceforge.net/tracker/?func=detail&atid=893831&aid=1807620&group_id=180599
>>>
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