Re: [Xen-devel] 4.4.0-rc2 tagged

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 14/01/2014 22:49, Don Slutz wrote:
> On 01/14/14 11:29, Ian Campbell wrote:
>> We've just tagged 4.4.0-rc2, please test and report bugs.
>>
>> The tarball can be downloaded here:
>>
>> http://bits.xensource.com/oss-xen/release/4.4.0-rc2/xen-4.4.0-rc2.tar.gz
>>
>> Ian.
>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxx
>> http://lists.xen.org/xen-devel
>
> This tarball does not build on CentOS 5.10:
>
>
> gcc -O1 -fno-omit-frame-pointer -m64 -g -fno-strict-aliasing
> -std=gnu99 -Wall -Wstrict-prototypes -Wdeclaration-after-statement
> -I/home/don/xen-4.4.0-rc2/xen/include
> -I/home/don/xen-4.4.0-rc2/xen/include/asm-x86/mach-generic
> -I/home/don/xen-4.4.0-rc2/xen/include/asm-x86/mach-default
> -msoft-float -fno-stack-protector -fno-exceptions -Wnested-externs
> -DHAVE_GAS_VMX -mno-red-zone -mno-sse -fpic
> -fno-asynchronous-unwind-tables -DGCC_HAS_VISIBILITY_ATTRIBUTE
> -fno-builtin -fno-common -Werror -Wredundant-decls -Wno-pointer-arith
> -pipe -g -D__XEN__ -include
> /home/don/xen-4.4.0-rc2/xen/include/xen/config.h -nostdinc
> -iwithprefix include -fno-optimize-sibling-calls -DVERBOSE -DHAS_ACPI
> -DHAS_GDBSX -DHAS_PASSTHROUGH -DHAS_PCI -DHAS_IOPORTS
> -fno-omit-frame-pointer -DCONFIG_FRAME_POINTER -MMD -MF .memory.o.d -c
> memory.c -o memory.o
> cc1: warnings being treated as errors
> memory.c: In function 'compat_memory_op':
> memory.c:213: warning: comparison is always true due to limited range
> of data type
> memory.c:214: warning: comparison is always true due to limited range
> of data type
> memory.c:215: warning: comparison is always true due to limited range
> of data type
> make[5]: *** [memory.o] Error 1
> make[5]: Leaving directory `/home/don/xen-4.4.0-rc2/xen/common/compat'
> make[4]: *** [compat/built_in.o] Error 2
> make[4]: Leaving directory `/home/don/xen-4.4.0-rc2/xen/common'
> make[3]: *** [/home/don/xen-4.4.0-rc2/xen/common/built_in.o] Error 2
> make[3]: Leaving directory `/home/don/xen-4.4.0-rc2/xen/arch/x86'
> make[2]: *** [/home/don/xen-4.4.0-rc2/xen/xen] Error 2
> make[2]: Leaving directory `/home/don/xen-4.4.0-rc2/xen'
> make[1]: *** [install] Error 2
> make[1]: Leaving directory `/home/don/xen-4.4.0-rc2/xen'
> make: *** [install-xen] Error 2
> dcs-xen-53:~/xen-4.4.0-rc2>uname -a
> Linux dcs-xen-53 2.6.18-371.el5xen #1 SMP Tue Oct 1 09:15:30 EDT 2013
> x86_64 x86_64 x86_64 GNU/Linux
> dcs-xen-53:~/xen-4.4.0-rc2>cat /etc/redhat-release
> CentOS release 5.10 (Final)
> dcs-xen-53:~/xen-4.4.0-rc2>gcc -v
> Using built-in specs.
> Target: x86_64-redhat-linux
> Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
> --infodir=/usr/share/info --enable-shared --enable-threads=posix
> --enable-checking=release --with-system-zlib --enable-__cxa_atexit
> --disable-libunwind-exceptions --enable-libgcj-multifile
> --enable-languages=c,c++,objc,obj-c++,java,fortran,ada
> --enable-java-awt=gtk --disable-dssi --disable-plugin
> --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre
> --with-cpu=generic --host=x86_64-redhat-linux
> Thread model: posix
> gcc version 4.1.2 20080704 (Red Hat 4.1.2-54)

I have also just encountered this build error, but am currently on the
fence as to whether it is a compiler bug in 4.1.2 or bad code.  Using
newer compilers causes the complaint to go away.  I would certainly like
to hope that compat_handle_ok() is correct, and does appear to be
correct from code inspection.

The if statement becomes gigantic after preprocessing, and I ran out of
effort today to sanitise the preprocessed output and check it for
correctness.  (At the very least, it would be kind to the compiler to
factor out the paging_mode_external(current->domain) check and degrade
the compat_handle_okay()s to compat_array_access_ok())

~Andrew

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