Re: [Qemu-devel] [PATCH qemu v2 0/4] spapr_pci, vfio: NVIDIA V100 + POWER9 passthrough

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 15/02/2019 16:21, David Gibson wrote:
> On Fri, Feb 15, 2019 at 03:34:52PM +1100, Alexey Kardashevskiy wrote:
>>
>>
>> On 15/02/2019 14:54, David Gibson wrote:
>>> On Fri, Feb 15, 2019 at 02:32:14PM +1100, Alexey Kardashevskiy wrote:
>>>>
>>>>
>>>> On 15/02/2019 14:24, David Gibson wrote:
>>>>> On Fri, Feb 15, 2019 at 11:35:02AM +1100, Alexey Kardashevskiy wrote:
>>>>>>
>>>>>>
>>>>>> On 15/02/2019 10:37, Alex Williamson wrote:
>>>>>>> On Thu, 14 Feb 2019 16:21:40 +1100
>>>>>>> Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
>>>>>>>
>>>>>>>> This is for passing through NVIDIA V100 GPUs on POWER9 systems.
>>>>>>>>
>>>>>>>> This implements a subdriver for NVIDIA V100 GPU with coherent memory and
>>>>>>>> NPU/ATS support available in the POWER9 CPU.
>>>>>>>>
>>>>>>>> 1/4 is a preparation for bigger DMA windows.
>>>>>>>> 2/4 is a small cleanup.
>>>>>>>>
>>>>>>>> Here is the kernel driver:
>>>>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/vfio/pci?h=v5.0-rc6&id=7f92891778dff62303c070ac81de7b7d80de331a
>>>>>>>>
>>>>>>>> SLOF changes already went in.
>>>>>>>>
>>>>>>>> This depends on "pci: Move NVIDIA vendor id to the rest of ids" (posted separately).
>>>>>>>
>>>>>>> TBH, I'm not sure it was the best idea to let it live or die on it's
>>>>>>> own when it now creates a build dependency for this series.
>>>>>> I am sure that patch is disgustingly primitive and can make it to
>>>>>> upstream in just one click and the rest of the series will take more
>>>>>> time anyway (always does :) ).
>>>>>>
>>>>>>>> This is based on sha1
>>>>>>>> 1ea6057 Mark Cave-Ayland "mac_newworld: change default NIC to sungem for mac99 machine".
>>>>>>>
>>>>>>> Perhaps this is why it doesn't apply cleanly against qemu.git.  Are
>>>>>>> there dependencies we need to wait for in the ppc tree as well?
>>>>>>
>>>>>> There are few changes in spapr_pci so conflicts are possible, every time
>>>>>> when David updates his tree and I rebase I get some minor ones.
>>>>>>
>>>>>>>> Please comment. Thanks.
>>>>>>>
>>>>>>> Besides the build dependency on PCI_VENDOR_ID_NVIDIA, I also get this:
>>>>>>>
>>>>>>> .../qemu.git/hw/vfio/spapr.c: In function ‘vfio_spapr_create_window’:
>>>>>>> .../qemu.git/hw/vfio/spapr.c:212:9: error: ‘ret’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>>>>>>          error_report("Failed to create a window, ret = %d (%m)", ret);
>>>>>>>          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>>>> cc1: all warnings being treated as errors
>>>>>>
>>>>>> Agrh. How exactly do you make them errors, not warnings? I get no
>>>>>> warning/error with --disable-werror but not having  --disable-werror
>>>>>> prints warnings, not errors so it does not fail the build and easy to miss.
>>>>>
>>>>> Are you sure it's printing warnings with --enable-werror?  Otherwise
>>>>> it sounds like you just have a compiler version that's not picking
>>>>> this up.
>>>>
>>>> Ah, here is my mistake - I thought not having --disable-werror means
>>>> that it is enabled as ./configure does not advertise  "--enable-werror":
>>>>
>>>> [fstn1-p1 qemu]$ ./configure --help | grep werror
>>>>   --disable-werror         disable compilation abort on warning
>>>>
>>>>
>>>> Apparently it is a tri-state flag :)
>>>
>>> Um.. no.. I believe it should be on by default as well, I was just
>>> saying --enable-werror because I thought it was clearer than the
>>> double negative in "without --disable-werror".
>>
>> The default value of werror is "":
>>
>> https://git.qemu.org/?p=qemu.git;a=blob;f=configure;h=a61682c3c727f467ce2710c7469a33b261da8ff6;hb=HEAD#l935
> 
> Which turns into a "yes" on Linux - see line 1835-1844.


No it does not - the 'test -d "$source_path/.git"' fails as "git
worktree" makes .git a file, not a folder.



-- 
Alexey