Hi, > > Hi Yamato-san, > > > On 2024-08-06 04:43, Masatake YAMATO wrote: >> Though drmCommandWriteRead() is used in libdrm [1], >> DRM_IOCTL_AMDGPU_GEM_VA uses DRM_IOW for encoding. >> >> [1] https://gitlab.freedesktop.org/mesa/drm/-/blob/main/amdgpu/amdgpu_bo.c?ref_type=heads > > AFAICT libdrm doesn't read from the struct drm_amdgpu_gem_va it passes to the ioctl after the latter returns though. > > Also, while amdgpu_gem_va_ioctl (the ioctl implementation in the kernel) modifies the struct: > > args->va_address &= AMDGPU_GMC_HOLE_MASK; > > that looks like an implementation detail which could be avoided if necessary, and shouldn't be propagated back to user space. > > > I'd suggest fixing libdrm to use drmCommandWrite instead. Thank you. After reading this mail, I inspected drm_ioctl.c. I was surprised that drm_ioctl() uses only the offset from DRM_COMMAND_BASE when choosing the real handler for a cmd. Therefore we can switch from drmCommandWriteRead to drmCommandWrite without breaking applications using the library. Masatake YAMATO > > -- > Earthling Michel Dänzer \ GNOME / Xwayland / Mesa developer > https://redhat.com \ Libre software enthusiast >
