README revision 1.1.1.4
1 1.1 mrg What are these headers ? 2 1.1 mrg ------------------------ 3 1.1 mrg This is the canonical source of drm headers that user space should use for 4 1.1 mrg communicating with the kernel DRM subsystem. 5 1.1 mrg 6 1.1 mrg They flow from the kernel, thus any changes must be merged there first. 7 1.1 mrg Do _not_ attempt to "fix" these by deviating from the kernel ones ! 8 1.1 mrg 9 1.1 mrg 10 1.1 mrg Non-linux platforms - changes/patches 11 1.1 mrg ------------------------------------- 12 1.1 mrg If your platform has local changes, please send them upstream for inclusion. 13 1.1 mrg Even if your patches don't get accepted in their current form, devs will 14 1.1 mrg give you feedback on how to address things properly. 15 1.1 mrg 16 1.1 mrg git send-email --subject-prefix="PATCH libdrm" your patches to dri-devel 17 1.1 mrg mailing list. 18 1.1 mrg 19 1.1 mrg Before doing so, please consider the following: 20 1.1 mrg - Have the [libdrm vs kernel] headers on your platform deviated ? 21 1.1 mrg Consider unifying them first. 22 1.1 mrg 23 1.1 mrg - Have you introduced additional ABI that's not available in Linux ? 24 1.1 mrg Propose it for [Linux kernel] upstream inclusion. 25 1.1 mrg If that doesn't work out (hopefully it never does), move it to another header 26 1.1 mrg and/or keep the change(s) local ? 27 1.1 mrg 28 1.1 mrg - Are your changes DRI1/UMS specific ? 29 1.1 mrg There is virtually no interest/power in keeping those legacy interfaces. They 30 1.1 mrg are around due to the kernel "thou shalt not break existing user space" rule. 31 1.1 mrg 32 1.1 mrg Consider porting the driver to DRI2/KMS - all (almost?) sensible hardware is 33 1.1 mrg capable of supporting those. 34 1.1 mrg 35 1.1 mrg 36 1.1 mrg Which headers go where ? 37 1.1 mrg ------------------------ 38 1.1 mrg A snipped from the, now removed, Makefile.am used to state: 39 1.1 mrg 40 1.1 mrg XXX airlied says, nothing besides *_drm.h and drm*.h should be necessary. 41 1.1 mrg however, r300 and via need their reg headers installed in order to build. 42 1.1 mrg better solutions are welcome. 43 1.1 mrg 44 1.1 mrg Obviously the r300 and via headers are no longer around ;-) 45 1.1 mrg 46 1.1 mrg Reason behind is that the drm headers can be used as a basic communications 47 1.1 mrg channel with the respective kernel modules. If more advanced functionality is 48 1.1 mrg required one can pull the specific libdrm_$driver which is free to pull 49 1.1 mrg additional files from the kernel. 50 1.1 mrg 51 1.1 mrg For example: nouveau has nouveau/nvif/*.h while vc4 has vc4/*.h 52 1.1 mrg 53 1.1 mrg If your driver is still in prototyping/staging state, consider moving the 54 1.1 mrg $driver_drm.h into $driver and _not_ installing it. An header providing opaque 55 1.1 mrg definitions and access [via $driver_drmif.h or similar] would be better fit. 56 1.1 mrg 57 1.1 mrg 58 1.1 mrg When and which headers to update 59 1.1 mrg -------------------------------- 60 1.1 mrg Ideally all files will be synced (updated) with the latest released kernel on 61 1.1 mrg each libdrm release. Sadly that's not yet possible since quite a few headers 62 1.1 mrg differ significantly - see Outdated or Broken Headers section below. 63 1.1 mrg 64 1.1 mrg That said, it's up-to the individual developers to sync with newer version 65 1.1 mrg (from drm-next) as they see fit. 66 1.1 mrg 67 1.1 mrg 68 1.1 mrg When and how to update these files 69 1.1 mrg ---------------------------------- 70 1.1.1.2 mrg Note: One should not do _any_ changes to the files apart from the steps below. 71 1.1.1.2 mrg 72 1.1 mrg In order to update the files do the following: 73 1.1 mrg - Switch to a Linux kernel tree/branch which is not rebased. 74 1.1.1.4 mrg For example: drm-next (https://cgit.freedesktop.org/drm/drm) 75 1.1 mrg - Install the headers via `make headers_install' to a separate location. 76 1.1 mrg - Copy the drm header[s] + git add + git commit. 77 1.1 mrg - Note: Your commit message must include: 78 1.1 mrg a) Brief summary on the delta. If there's any change that looks like an 79 1.1 mrg API/ABI break one _must_ explicitly state why it's safe to do so. 80 1.1 mrg b) "Generated using make headers_install." 81 1.1 mrg c) "Generated from $tree/branch commit $sha" 82 1.1 mrg 83 1.1 mrg 84 1.1 mrg Outdated or Broken Headers 85 1.1 mrg -------------------------- 86 1.1 mrg This section contains a list of headers and the respective "issues" they might 87 1.1 mrg have relative to their kernel equivalent. 88 1.1 mrg 89 1.1 mrg Most UMS headers: 90 1.1 mrg - Not using fixed size integers - compat ioctls are broken. 91 1.1 mrg Status: ? 92 1.1 mrg Promote to fixed size ints, which match the current (32bit) ones. 93 1.1 mrg 94 1.1 mrg nouveau_drm.h 95 1.1 mrg - Missing macros NOUVEAU_GETPARAM*, NOUVEAU_DRM_HEADER_PATCHLEVEL, structs, 96 1.1.1.3 mrg enums 97 1.1.1.4 mrg Status: Deliberate UABI choice; nouveau hides the exact kernel ABI behind libdrm 98 1.1 mrg 99 1.1 mrg r128_drm.h 100 1.1 mrg - Broken compat ioctls. 101 1.1 mrg 102 1.1 mrg radeon_drm.h 103 1.1.1.3 mrg - Missing RADEON_TILING_R600_NO_SCANOUT, CIK_TILE_MODE_*, broken UMS ioctls 104 1.1 mrg - Both kernel and libdrm: missing padding - 105 1.1 mrg drm_radeon_gem_{create,{g,s}et_tiling,set_domain} others ? 106 1.1 mrg Status: ? 107 1.1 mrg 108 1.1 mrg savage_drm.h 109 1.1 mrg - Renamed ioctls - DRM_IOCTL_SAVAGE_{,BCI}_EVENT_EMIT, compat ioctls are broken. 110 1.1 mrg Status: ? 111 1.1 mrg 112 1.1 mrg sis_drm.h 113 1.1 mrg - Borken ioctls + libdrm uses int vs kernel long 114 1.1 mrg Status: ? 115 1.1 mrg 116 1.1 mrg via_drm.h 117 1.1 mrg - Borken ioctls - libdrm int vs kernel long 118 1.1 mrg Status: ? 119 1.1 mrg 120 1.1 mrg 121 1.1 mrg omap_drm.h (living in $TOP/omap) 122 1.1 mrg - License mismatch, missing DRM_IOCTL_OMAP_GEM_NEW and related struct 123 1.1 mrg Status: ? 124 1.1 mrg 125 1.1 mrg exynos_drm.h (living in $TOP/exynos) 126 1.1 mrg - License mismatch, now using fixed size ints (but not everywhere). Lots of 127 1.1 mrg new stuff. 128 1.1 mrg Status: ? 129
Indexes created Mon Oct 26 00:26:21 UTC 2026