Why has to offer "/dev/drv/render128" fd when running ROCm demo?

[Christian König]

Hi Zicao,

that won't work any more the render Node is mandatory for correct ROCm 
operation by now.

Regards,
Christian.

Am 06.03.24 um 06:25 schrieb 曹子龙:
> Hi felix:
>    Thanks for your kindly help.
>
> i still has a question, if on a pure-compute platform, which has no 
> /dev/dri/render node, but only with a single /dev/kfd node, how the 
> compue scenario works since that wei have no "render" fd exists?
> is such platfom(without render node) exists?
>
>  thanks for your kindly help.!
>
> BRs
> zlcao.
>
>
>
>
>
> At 2024-03-06 04:43:30, "Kuehling, Felix" <Felix.Kuehling at amd.com> wrote:
>
>     [AMD Official Use Only - General]
>
>
>     I already answered this question in a reply to another email that
>     was addressed to me:
>
>     The render nodes are used for CPU mapping of VRAM with mmap calls
>     and an offset that identifies the BO. The render node also creates
>     the GPU virtual address space that is used by KFD to create the
>     GPU memory mappings. Applications that use both graphics and
>     compute can share the same GPU virtual address space in this way.
>
>     Zlcao, in the future, this type of question may be better
>     addressed to a mailing list such as amd-gfx at lists.freedesktop.org,
>     instead of writing separately to different maintainers.
>
>     Regards,
>       Felix
>
>     *From:*Deucher, Alexander <Alexander.Deucher at amd.com>
>     *Sent:* Tuesday, March 5, 2024 3:17 PM
>     *To:* 曹子龙<gainerying at 163.com>; Kuehling, Felix
>     <Felix.Kuehling at amd.com>; Yat Sin, David <David.YatSin at amd.com>
>     *Subject:* Re: Why has to offer "/dev/drv/render128" fd when
>     running ROCm demo?
>
>     [AMD Official Use Only - General]
>
>     + Felix, David to comment.
>
>     ------------------------------------------------------------------------
>
>     *From:*曹子龙<gainerying at 163.com <mailto:gainerying at 163.com>>
>     *Sent:* Tuesday, March 5, 2024 8:46 AM
>     *To:* Deucher, Alexander <Alexander.Deucher at amd.com
>     <mailto:Alexander.Deucher at amd.com>>
>     *Subject:* Why has to offer "/dev/drv/render128" fd when running
>     ROCm demo?
>
>     Hi alexander.:
>
>         sorry for bother. but i really need some help to deal with my
>     puzzle.
>
>     i am a freshman to AMD GPU Driver, NOW i am trying to write a
>     simple demo to use "/dev/kfd" and do some  vram alloc/free tests, 
>     but i found you must do the right "AMDKFD_IOC_ACQUIRE_VM" ioctl
>     comamnd before you try GPU to do vram allocation and other
>     things.  from the kfd driver code,the pre-condition to do the
>     right "AMDKFD_IOC_ACQUIRE_VM" is to offer a "/dev/drv/render128"
>     fd  to the parameters.
>
>     so, why need to do this? kfd is used for compute, but
>     "/dev/dri/render128" is specify to gfx usaged, why must open the
>     "/dev/dri/render128" during the KFD compute scenario?
>
>     thanks for your kindly help!
>
>     BRs
>
>     zlcao.
>
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