Re: [Qemu-devel] [RFC PATCH] Allow building without graphics support

[Stefan Weil <sw@weilnetz.de>]

Am 13.12.2012 01:48, schrieb Scott Wood:
> On 12/12/2012 12:46:44 AM, Stefan Weil wrote:
>> Am 12.12.2012 04:18, schrieb Scott Wood:
>>> QEMU is sometimes used in embedded contexts, where graphical support
>>> is unnecessary.  The ability to turn off graphics support not only
>>> saves some space, but it eliminates the dependency on pixman.
>>>
>>> Signed-off-by: Scott Wood <scottwood@freescale.com>
>>> ---
>>> There are undoubtedly some rough edges that need to be cleaned up and
>>> other parts of graphics code that could be compiled out -- this is 
>>> mainly
>>> meant to see what people think of the concept.
>>>
>>> My immediate motivation was that the QEMU-supplied pixman was being a
>>> pain to cross compile (especially without hacking up the generated QEMU
>>> makefiles to pass additional things to pixman's configure), and in
>>> general it would be nice to not have to carry around graphical baggage
>>> when running on hardware that doesn't even have a display (so I was 
>>> more
>>> inclined to do this than to spend effort fixing the pixman build).
>>
>> Hi,
>>
>> cross compilation works for me with the internal pixman.
>> Here is an example which I use to compile Windows 64 bit
>> executables on Debian:
>>
>> ./configure' '--cross-prefix=amd64-mingw32msvc-'
>>
>> Are there still problems with cross compilation in latest QEMU?
>
> It doesn't seem to like my --cross-prefix being a full path rather 
> than being a recognized target pattern:
>
> checking host system type... Invalid configuration 
> `/home/scott/fsl/tc/gcc-4.5.55-eglibc-2.11.55/powerpc-linux-gnu/bin/powerpc-linux-gnu': 
> machine 
> `/home/scott/fsl/tc/gcc-4.5.55-eglibc-2.11.55/powerpc-linux-gnu/bin/powerpc' 
> not recognized
> configure: error: /bin/bash /home/scott/fsl/git/qemu/pixman/config.sub 
> /home/scott/fsl/tc/gcc-4.5.55-eglibc-2.11.55/powerpc-linux-gnu/bin/powerpc-linux-gnu 
> failed
> make: *** [pixman/Makefile] Error 1
>
> When I forced --host=powerpc-linux into the pixman configure command 
> in QEMU's generated Makefile, it got past that, but it built 
> everything with the native compiler:
>
> checking build system type... x86_64-unknown-linux-gnu
> checking host system type... powerpc-unknown-linux-gnu
> checking for powerpc-linux-gcc... no
> checking for gcc... gcc
>
> Looking a bit more closely, it seems that it's the QEMU rather than 
> pixman's autoconf that is making the bad assumption about the format 
> of --cross-prefix (I really wasn't up for wading in autoconf).  
> Running basename on cross-prefix and explicitly supplying CC and such 
> to pixman would help, though there still should be a way to pass in an 
> explicit host tuple if you have an unusually-named toolchain.
>
> -Scott

Indeed, --cross-prefixdoes not support absolute path names.

I assume that the executables in
/home/scott/fsl/tc/gcc-4.5.55-eglibc-2.11.55/powerpc-linux-gnu/binare 
without prefix
(gcc, ld, ...). Then there must also be the same executables with prefix
(powerpc-linux-gnu-gcc, powerpc-linux-gnu-ld, ...). These must be 
somewhere in PATH.
Use --cross-prefix=powerpc-linux-gnu-(note the "-" at the end).
Then pixman would be configured with --host=powerpc-linux-gnu and should 
find
the compiler. It won't find the compiler powerpc-linux-gcc when its real 
name is
powerpc-linux-gnu-gcc.

-Stefan