[SLOF] [PATCH 3/4] fbuffer: Implement MRMOVE as an accelerated primitive

Nikunj A Dadhania nikunj at linux.vnet.ibm.com
Wed Sep 9 21:37:19 AEST 2015

Thomas Huth <thuth at redhat.com> writes:

> On 09/09/15 13:05, Nikunj A Dadhania wrote:
>> Thomas Huth <thuth at redhat.com> writes:
>>> On 09/09/15 08:45, Nikunj A Dadhania wrote:
>>>> Thomas Huth <thuth at redhat.com> writes:
>>>>> On 03/08/15 17:53, Thomas Huth wrote:
>>>>>> On 03/08/15 12:37, Nikunj A Dadhania wrote:
>>>>>>> Thomas Huth <thuth at redhat.com> writes:
>>>>>>>> The character drawing function fb8-draw-character uses "mrmove"
>>>>>>>> (which moves main memory contents to IO memory) to copy the data
>>>>>>>> of the character from main memory to the frame buffer. However,
>>>>>>>> the current implementation of "mrmove"  performs quite badly on
>>>>>>>> board-qemu since it triggers a hypercall for each memory access
>>>>>>>> (e.g. for each 8 bytes that are transfered).
>>>>>>>> But since the KVMPPC_H_LOGICAL_MEMOP hypercall can transfer bigger
>>>>>>>> regions at once, we can accelerate the character drawing quite a
>>>>>>>> bit by simply mapping the "mrmove" to the same macro that is
>>>>>>>> already used for the "rmove". For keeping board-js2x in sync,
>>>>>>>> this patch also transforms the "mrmove" for js2x into primitives.
>>>>>>>> Signed-off-by: Thomas Huth <thuth at redhat.com>
>>>>>>> I dont have a js2x handy, did you test this on js2x?
>>>>>> No, sorry, unfortunately, I also was not able to test this on js2x yet.
>>>>>> I still have a YDL PowerStation somewhere in a corner of my flat, but
>>>>>> it's currently not set up ... will do that one day when I got enough
>>>>>> spare time again, but that won't happen within the next few weeks (KVM
>>>>>> forum's ahead!). So if there are problems, I'll fix them up as soon as I
>>>>>> got the PowerStation running again (and I guess there might be other
>>>>>> problems, too, since board-js2x hardly got any testing within the last
>>>>>> months/years, I think).
>>>>> FWIW, I've recently dusted off my PowerStation and gave it a try...
>>>>> the HEAD of the SLOF master branch is unfortunately quite broken on js2x
>>>>> nowadays (I'll try to send some first fixes later), but I was able to
>>>>> cherry-pick the fbuffer acceleration patches to an older level of SLOF
>>>>> from 2012 which was still working nicely.
>>>> TCG seem to be broken with this new series, git bisect pointed to:
>>>> 59a135e fbuffer: Implement MRMOVE as an accelerated primitive
>>>> I havent looked into detail of why its failing though.
>>> It seems to work fine for me here (SLOF master and QEMU master
>>> branch). Which version of QEMU did you use? 
>> QEMU: fc04a73 Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20150908' into staging
>> SLOF: 811277a version: update to 20150813
>>> Which command line parameters?
>>         ./ppc64-softmmu/qemu-system-ppc64 -machine pseries -m 2048  -serial stdio
> I've just tried the very same versions, with the very same parameters,
> and it is working nicely here! Very strange...
>>         VNC server running on `'
>> 	SLOF **********************************************************************
>> 	QEMU Starting
>> 	 Build Date = Sep  9 2015 16:30:15
>> 	 FW Version = git-811277ac91f674a9
>> 	 Press "s" to enter Open Firmware.
>> 	Cannot open file : fbuffer.fs
> Sounds like the boot_rom.bin / slof.bin maybe has not been built
> correctly ... what do you get when you run:
> strings boot_rom.bin | grep fbuffer.fs

$ strings boot_rom.bin | grep fbuffer.fs
include fbuffer.fs


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