[Rpm-maint] Multiple ABI architectures (parallel installation, detection, handling)

[Panu Matilainen]

On 10/27/2011 12:00 AM, Dennis Gilmore wrote:
[...big snip...]
>>> its not sufficient. it evaluates to armv7l on a hardware floating
>>> point system. we would need it to be armv7hl or armv7hnl to give yum
>>> the info it needs
>>
>> maybe _target_cpu could be used
>>
>> though it would need a dict of compatiable arches
>>
>> [dennis at panda02 ~]$ rpm --showrc |grep arm
>> build arch            : armv7hnl
>> compatible build archs: armv7hnl armv7hl noarch
>> install arch          : armv7hnl
>> compatible archs      : armv7hnl armv7hl noarch
>> optflags              : -O2 -g -march=armv7-a -mfloat-abi=hard
>> -mfpu=neon -mthumb gpg --batch --no-verbose --no-armor
>> --passphrase-fd 3
>> - -14: __isa_name	armv7hnl
>> - -14: _arch	arm
>> - -14: _build_arch	arm
>> - -14: _host	armv7l-unknown-linux-gnueabi
>> - -14: _host_cpu	armv7l
>> - -11: _target	armv7hnl-linux
>> - -11= _target_cpu	armv7hnl
>> - -14: arm	armv3l armv4b armv4l armv4tl armv5tel armv5tejl
>> armv6l armv7l armv7hl armv7nhl
>> - -11: optflags	-O2 -g -march=armv7-a -mfloat-abi=hard
>> -mfpu=neon -mthumb
>>
>>
>> [root at trimslice01 ~]#  rpm --showrc |grep arm
>> build arch            : armv7hl
>> compatible build archs: armv7hl noarch
>> install arch          : armv7hl
>> compatible archs      : armv7hl noarch
>> optflags              : -O2 -g -march=armv7-a -mfloat-abi=hard
>> -mfpu=vfpv3-d16 -mthumb gpg --batch --no-verbose --no-armor
>> --passphrase-fd 3
>> - -14: __isa_name	armv7hl
>> - -14: _arch	arm
>> - -14: _build_arch	arm
>> - -14: _host	armv7l-unknown-linux-gnueabi
>> - -14: _host_cpu	armv7l
>> - -11: _target	armv7hl-linux
>> - -11= _target_cpu	armv7hl
>> - -14: arm	armv3l armv4b armv4l armv4tl armv5tel armv5tejl
>> armv6l armv7l armv7hl armv7nhl
>> - -11: optflags	-O2 -g -march=armv7-a -mfloat-abi=hard
>> -mfpu=vfpv3-d16 -mthumb
>>
>>
>> the first output is a system that has a neon simd unit and the second
>> is without it. any software that can run on the second can also run on
>> the first. __isa_name really should be the same on both.
>>
>> long term maybe we can do something better. right now im looking for a
>> way to enable yum to detect the arches correctly without it resorting
>> to things like running readelf to determine the abi of the running
>> system.  since its noarch we cant just patch things in conditionally.
>>
>> Dennis
>
>
> ok since i have a ton of the oddball hardware here
>
> is there someway to get whats setting "compatible archs" in --showrc?
> i ask because
>
>   rpm --showrc |grep armv7
> build arch            : armv7hnl
> compatible build archs: armv7hnl armv7hl noarch
> install arch          : armv7hnl
> compatible archs      : armv7hnl armv7hl noarch
> optflags              : -O2 -g -march=armv7-a -mfloat-abi=hard
>   -mfpu=neon -mthumb -14: __isa_name	armv7hnl
> - -14: _host	armv7l-unknown-linux-gnueabi
> - -14: _host_cpu	armv7l
> - -11: _target	armv7hnl-linux
> - -11= _target_cpu	armv7hnl
> - -14: arm	armv3l armv4b armv4l armv4tl armv5tel armv5tejl armv6l
>   armv7l armv7hl armv7nhl -11: optflags	-O2 -g -march=armv7-a
>   -mfloat-abi=hard -mfpu=neon -mthumb
>
> rpm --showrc |grep sparc
> build arch            : sparc64
> compatible build archs: sparc64v sparc64 sparcv9v sparcv9 sparcv8 sparc
> noarch install arch          : sparc64v
> compatible archs      : sparc64v sparc64 sparcv9v sparcv9 sparcv8 sparc
> noarch -14: _arch	sparc
> - -14: _build_arch	sparc
> - -14: _host	sparc-unknown-linux-gnu
> - -14: _host_cpu	sparc
> - -11: _target	sparc64-linux
> - -11= _target_cpu	sparc64
> - -11: optflags	%{__global_cflags} -m64 -mcpu=ultrasparc
> - -14: sparc	sparc sparcv8 sparcv9 sparcv9v sparc64 sparc64v
>
>
> _host_cpu and _target_cpu on sparc doesnt give me a way to work out
> that im on a niagara box  but in both cases i could work out whats
> needed by the info thats in "compatible archs" looking at rpmrc.c
> RPM_MACHTABLE_INSTARCH is whats used internal. is that available at all?
>
> on a niagara box
> In [2]: rpm.expandMacro('%{_target_cpu}')
> Out[2]: 'sparc64'
>
> on a trimslice running hardfp but without a neon simd
> In [9]: rpm.expandMacro('%{_target_cpu}')
> Out[9]: 'armv7hl'

Yup, my bad - neither macro ends up containing the "install arch" in the 
end. The target gets set for "install arch" during initialization (to 
read the correct platform file) but is then reset in the bowels of rpmrc.

The arch (compat and other) tables aren't really exported anywhere at 
all. In python the only thing is rpm.archscore() which returns non-zero 
values for arch strings that are compatible with the system architecture 
according to rpm's internal knowledge (configuration & detected stuff). 
But then yum doesn't use even that, it does its own hardware detection 
by reading /proc/cpuinfo and all (see rpmUtils/arch.py) and uses its own 
hardcoded compatibility tables.

Maybe rpm should export more of selected bits of its internal hw info. 
But even if it did, yum is unlikely to rely on that info being available 
anytime soon. So you'll end up (re)writing the ARM detection in yum 
anyway, might as well just add it there now and move on to other issues 
- reworking the entire way yum vs rpm arch detection is just not going 
to happen in the current stable releases (talking of the rpm/yum 
versions included in F15-16 and probably F17 too)

	- Panu -