{"id":100227,"date":"2026-09-04T07:48:56","date_gmt":"2026-09-03T23:48:56","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/100227.html"},"modified":"2026-09-04T07:48:56","modified_gmt":"2026-09-03T23:48:56","slug":"5-3-1-prime-%e7%9a%84%e4%b8%a4%e5%ba%a7%e6%a1%a5%ef%bc%9agem-%e2%86%94-dma-buf-%e6%a1%a5%e6%8e%a5%e5%9b%9e%e8%b0%83%e4%b8%8e-fd-handle-%e8%bd%ac%e6%8d%a2","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/100227.html","title":{"rendered":"5.3.1 PRIME \u7684\u4e24\u5ea7\u6865\uff1aGEM \u2194 dma-buf \u6865\u63a5\u56de\u8c03\u4e0e fd\/handle \u8f6c\u6362"},"content":{"rendered":"

5.2 \u8282 \u5206\u6790 \u4e86dma-buf \u8fd9\u5957\u300c\u8de8\u8bbe\u5907\u7f13\u51b2\u533a\u5171\u4eab\u300d\u7684\u901a\u7528\u673a\u5236，\u4f46\u5b83\u59cb\u7ec8\u505c\u5728 dma-buf \u81ea\u5df1\u7684\u62bd\u8c61\u5c42\u3002\u56de\u5230 DRM\/GEM \u7684\u573a\u666f：\u7528\u6237\u6001\u8bbf\u95ee BO \u7684\u63a5\u53e3\u662f\u4e00\u4e2a\u8fdb\u7a0b\u5185\u7684 GEM handle（\u4e00\u4e2a 32 \u4f4d\u6574\u6570），\u6e32\u67d3\u65f6\u7528 handle \u5f15\u7528 BO，\u63d0\u4ea4\u547d\u4ee4\u65f6\u7528 handle \u7d22\u5f15\u3002\u53ef handle \u53ea\u5728\u672c\u8fdb\u7a0b\u672c\u8bbe\u5907\u6709\u610f\u4e49，\u4e00\u65e6\u8981\u628a BO \u4ea4\u7ed9\u53e6\u4e00\u4e2a\u8fdb\u7a0b\u3001\u53e6\u4e00\u5757 GPU，\u5c31\u5fc5\u987b\u6362\u6210\u80fd\u8de8\u8fdb\u7a0b\u4f20\u9012\u7684 dma-buf fd\u3002\u7136\u540e fd \u8981\u53d8\u6210importer \u8fdb\u7a0b\u4e2d\u7684 handle \u624d\u80fd\u88ab\u7528\u6237\u6001\u8bbf\u95ee\u3002<\/p>\n

PRIME \u5c31\u662f GEM \u4e16\u754c\u4e0e dma-buf \u4e16\u754c\u4e4b\u95f4\u7684\u53cc\u5411\u6865：\u5b83\u628a\u300c\u8fdb\u7a0b\u79c1\u6709\u7684 handle\u300d\u7ffb\u8bd1\u6210\u300c\u53ef\u4f20\u9012\u7684 fd\u300d（\u5bfc\u51fa），\u53c8\u628a\u522b\u5904\u4f20\u6765\u7684\u300cfd\u300d\u7ffb\u8bd1\u56de\u300c\u672c\u8fdb\u7a0b\u7684 handle\u300d（\u5bfc\u5165）\u3002\u7528\u6237\u6001\u53ea\u9700\u4e24\u4e2a ioctl，\u5185\u6838\u5219\u7528\u4e00\u7ec4\u6865\u63a5\u56de\u8c03\u628a\u4e24\u5957\u5bf9\u8c61\u6a21\u578b\u7684\u751f\u547d\u5468\u671f\u3001\u5f15\u7528\u8ba1\u6570\u3001\u7f13\u5b58\u4e00\u4e00\u5bf9\u9f50\u3002<\/p>\n

1. \u4e24\u4e2a ioctl，\u4e24\u5ea7\u6865<\/h3>\n

\u7528\u6237\u6001\u7684\u5168\u90e8\u5165\u53e3\u5c31\u662f\u4e24\u4e2a\u5bf9\u79f0\u7684 ioctl：<\/p>\n\nioctl\u65b9\u5411\u5185\u6838\u5165\u53e3\u4f5c\u7528<\/tr>\n\n\n\n
DRM_IOCTL_PRIME_HANDLE_TO_FD<\/td>\n\u5bfc\u51fa<\/td>\ndrm_prime_handle_to_fd_ioctl \u2192 drm_gem_prime_handle_to_fd<\/td>\n\u672c\u8fdb\u7a0b handle \u2192 \u53ef\u4f20\u9012\u7684 dma-buf fd<\/td>\n<\/tr>\n
DRM_IOCTL_PRIME_FD_TO_HANDLE<\/td>\n\u5bfc\u5165<\/td>\ndrm_prime_fd_to_handle_ioctl \u2192 drm_gem_prime_fd_to_handle<\/td>\n\u522b\u5904\u4f20\u6765\u7684 fd \u2192 \u672c\u8fdb\u7a0b handle<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u4e24\u4e2a ioctl \u90fd\u7559\u4e86\u300c\u9a71\u52a8\u53ef\u8986\u76d6\u300d\u7684\u56de\u8c03：\u82e5 dev->driver->prime_handle_to_fd \/ prime_fd_to_handle \u975e\u7a7a\u5219\u7528\u9a71\u52a8\u81ea\u5df1\u7684，\u5426\u5219\u7528 DRM \u6838\u5fc3\u7684\u9ed8\u8ba4\u5b9e\u73b0\u3002\u7edd\u5927\u591a\u6570\u9a71\u52a8\u76f4\u63a5\u7528\u9ed8\u8ba4\u7684\u3002<\/p>\n

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<\/p>\n

\u8fdb\u7a0b B \/ GPU-1<\/p>\n

<\/span><\/p>\n

<\/p>\n

\u8fdb\u7a0b A \/ GPU-0<\/p>\n

<\/span><\/p>\n

<\/p>\n

HANDLE_TO_FD<\/p>\n

<\/span><\/p>\n

<\/p>\n

SCM_RIGHTS \u4f20\u9012 fd<\/p>\n

<\/span><\/p>\n

<\/p>\n

FD_TO_HANDLE<\/p>\n

<\/span><\/p>\n

<\/span><\/p>\n

<\/span><\/p>\n

<\/p>\n

GEM handle<\/p>\n

<\/span><\/p>\n

<\/p>\n

dma-buf fd<\/p>\n

<\/span><\/p>\n

<\/p>\n

dma-buf fd<\/p>\n

<\/span><\/p>\n

<\/p>\n

GEM handle<\/p>\n

<\/span><\/p>\n

<\/p>\n

\u540c\u4e00\u4e2a struct dma_buf\u540c\u4e00\u5757\u540e\u7aef\u5b58\u50a8<\/p>\n

<\/span><\/p>\n

2. \u5bfc\u51fa\u6865：handle \u2192 fd<\/h3>\n

drm_gem_prime_handle_to_fd() \u672c\u8eab\u53ea\u505a\u300c\u7533\u8bf7 fd \u2192 \u62ff dma_buf \u2192 \u5b89\u88c5 fd\u300d\u4e09\u6b65：<\/p>\n

int<\/span> drm_gem_prime_handle_to_fd<\/span>(<\/span>struct<\/span> drm_device<\/span> *<\/span>dev,<\/span> struct<\/span> drm_file<\/span> *<\/span>file_priv,<\/span>
\n uint32_t<\/span> handle,<\/span> uint32_t<\/span> flags,<\/span> int<\/span> *<\/span>prime_fd)<\/span>
\n{<\/span>
\n struct<\/span> dma_buf<\/span> *<\/span>dmabuf;<\/span>
\n int<\/span> fd =<\/span> get_unused_fd_flags<\/span>(<\/span>flags)<\/span>;<\/span> \/* 1. \u9884\u7559\u4e00\u4e2a\u7a7a fd *\/<\/span>
\n .<\/span>.<\/span>.<\/span>
\n dmabuf =<\/span> drm_gem_prime_handle_to_dmabuf<\/span>(<\/span>dev,<\/span> file_priv,<\/span> handle,<\/span> flags)<\/span>;<\/span> \/* 2. handle\u2192dma_buf *\/<\/span>
\n .<\/span>.<\/span>.<\/span>
\n fd_install<\/span>(<\/span>fd,<\/span> dmabuf-><\/span>file)<\/span>;<\/span> \/* 3. \u628a dma_buf \u7684 file \u88c5\u5230 fd \u4e0a *\/<\/span>
\n *<\/span>prime_fd =<\/span> fd;<\/span>
\n return<\/span> 0<\/span>;<\/span>
\n}<\/span><\/p>\n

\u771f\u6b63\u6709\u8bb2\u7a76\u7684\u662f\u7b2c 2 \u6b65 drm_gem_prime_handle_to_dmabuf()，\u5b83\u6309\u4e09\u79cd\u60c5\u51b5\u51b3\u5b9a dma_buf \u4ece\u54ea\u6765：<\/p>\n

\/* \u60c5\u51b5\u4e00：\u8fd9\u4e2a GEM \u5bf9\u8c61\u672c\u8eab\u5c31\u662f\u4ece\u522b\u5904\u5bfc\u5165\u6765\u7684 \u2192 \u590d\u7528\u539f\u59cb dma-buf *\/<\/span>
\n if<\/span> (<\/span>obj-><\/span>import_attach)<\/span> {<\/span>
\n dmabuf =<\/span> obj-><\/span>import_attach-><\/span>dmabuf;<\/span>
\n get_dma_buf<\/span>(<\/span>dmabuf)<\/span>;<\/span>
\n goto<\/span> out_have_obj;<\/span>
\n }<\/span><\/p>\n

\/* \u60c5\u51b5\u4e8c：\u4e4b\u524d\u5df2\u7ecf\u5bfc\u51fa\u8fc7 \u2192 \u590d\u7528\u7f13\u5b58\u7684 dma_buf（\u4e0d\u91cd\u590d\u521b\u5efa） *\/<\/span>
\n if<\/span> (<\/span>obj-><\/span>dma_buf)<\/span> {<\/span>
\n get_dma_buf<\/span>(<\/span>obj-><\/span>dma_buf)<\/span>;<\/span>
\n dmabuf =<\/span> obj-><\/span>dma_buf;<\/span>
\n goto<\/span> out_have_obj;<\/span>
\n }<\/span><\/p>\n

\/* \u60c5\u51b5\u4e09：\u7b2c\u4e00\u6b21\u5bfc\u51fa \u2192 \u771f\u6b63\u521b\u5efa\u5e76\u6ce8\u518c dma_buf *\/<\/span>
\n dmabuf =<\/span> export_and_register_object<\/span>(<\/span>dev,<\/span> obj,<\/span> flags)<\/span>;<\/span><\/p>\n

\u8fd9\u4e09\u4e2a\u5206\u652f\u4fdd\u8bc1\u4e86\u4e00\u6761\u5173\u952e\u4e0d\u53d8\u91cf\u2014\u2014\u540c\u4e00\u4e2a GEM \u5bf9\u8c61\u5728\u5176\u751f\u547d\u5468\u671f\u5185\u53ea\u5bf9\u5e94\u552f\u4e00\u4e00\u4e2a dma_buf：<\/p>\n

    \n
  • \u60c5\u51b5\u4e00（import_attach \u975e\u7a7a）：\u8fd9\u5757 BO \u662f\u5bfc\u5165\u6765\u7684\u300c\u5f71\u5b50\u5bf9\u8c61\u300d，\u5bfc\u51fa\u5b83\u65f6\u4e0d\u80fd\u518d\u5305\u4e00\u5c42，\u800c\u8981\u628a\u6700\u521d\u7684\u539f\u59cb dma-buf \u539f\u6837\u4ea4\u51fa\u53bb\u2014\u2014\u5426\u5219\u4f1a\u51fa\u73b0\u300cdma-buf \u5957 GEM \u5957 dma-buf\u300d\u7684\u8352\u8c2c\u5d4c\u5957\u3002<\/li>\n
  • \u60c5\u51b5\u4e8c（obj->dma_buf \u5df2\u7f13\u5b58）：\u66fe\u7ecf\u5bfc\u51fa\u8fc7，\u76f4\u63a5\u590d\u7528\u5e76 get_dma_buf \u52a0\u5f15\u7528，\u907f\u514d\u540c\u4e00 BO \u4ea7\u751f\u4e24\u4e2a\u4e92\u4e0d\u76f8\u5e72\u7684 dma_buf\u3002<\/li>\n
  • \u60c5\u51b5\u4e09：\u9996\u6b21\u5bfc\u51fa\u624d\u8d70 export_and_register_object，\u5185\u90e8\u6700\u7ec8\u8c03 obj->funcs->export（\u9ed8\u8ba4\u662f drm_gem_prime_export）\u771f\u6b63\u521b\u5efa dma_buf，\u5e76\u628a\u5b83\u7f13\u5b58\u8fdb obj->dma_buf\u3002<\/li>\n<\/ul>\n

    drm_gem_prime_export() \u5c31\u662f\u90a3\u4e2a\u300c\u771f\u6b63\u521b\u5efa\u300d\u7684\u9ed8\u8ba4\u5b9e\u73b0，\u5b83\u628a GEM \u5bf9\u8c61\u586b\u8fdb\u6807\u51c6\u7684 dma_buf_export_info：<\/p>\n

    struct<\/span> dma_buf<\/span> *<\/span>drm_gem_prime_export<\/span>(<\/span>struct<\/span> drm_gem_object<\/span> *<\/span>obj,<\/span> int<\/span> flags)<\/span>
    \n{<\/span>
    \n struct<\/span> dma_buf_export_info<\/span> exp_info =<\/span> {<\/span>
    \n .<\/span>exp_name =<\/span> KBUILD_MODNAME,<\/span>
    \n .<\/span>ops =<\/span> &<\/span>drm_gem_prime_dmabuf_ops,<\/span> \/* GEM \u4e13\u7528\u7684 dma_buf_ops *\/<\/span>
    \n .<\/span>size =<\/span> obj-><\/span>size,<\/span>
    \n .<\/span>flags =<\/span> flags,<\/span>
    \n .<\/span>priv =<\/span> obj,<\/span> \/* dma_buf->priv \u6307\u56de GEM \u5bf9\u8c61 *\/<\/span>
    \n .<\/span>resv =<\/span> obj-><\/span>resv,<\/span> \/* \u5171\u7528\u540c\u4e00\u4e2a reservation object *\/<\/span>
    \n }<\/span>;<\/span>
    \n return<\/span> drm_gem_dmabuf_export<\/span>(<\/span>dev,<\/span> &<\/span>exp_info)<\/span>;<\/span>
    \n}<\/span><\/p>\n

    \u4e24\u4e2a\u5b57\u6bb5\u503c\u5f97\u8bb0\u4f4f：priv = obj \u5efa\u7acb\u4e86\u300cdma_buf \u2192 GEM \u5bf9\u8c61\u300d\u7684\u53cd\u5411\u6307\u9488（\u524d\u51e0\u8282 amdgpu \u91cc gem_to_amdgpu_bo(dma_buf->priv) \u5c31\u9760\u5b83）；resv = obj->resv \u8ba9 dma-buf \u4e0e GEM \u5bf9\u8c61\u5171\u4eab\u540c\u4e00\u628a\u540c\u6b65\u9501\u4e0e fence \u5bb9\u5668，\u8fd9\u662f\u9690\u5f0f\u540c\u6b65（6.3）\u80fd\u8de8\u8bbe\u5907\u751f\u6548\u7684\u6839\u57fa\u3002<\/p>\n

    ops = &drm_gem_prime_dmabuf_ops \u5219\u662f\u8fd9\u5ea7\u6865\u7684\u53e6\u4e00\u534a\u2014\u2014\u5b83\u628a dma-buf \u7684\u901a\u7528\u56de\u8c03\u8f6c\u63a5\u5230 GEM \u7684 drm_gem_object_funcs：<\/p>\n\ndma_buf_ops \u56de\u8c03GEM \u6865\u63a5\u5b9e\u73b0\u6700\u7ec8\u59d4\u6d3e\u5230<\/tr>\n\n\n\n\n\n\n\n
    attach<\/td>\ndrm_gem_map_attach<\/td>\nobj->funcs->pin<\/td>\n<\/tr>\n
    map_dma_buf<\/td>\ndrm_gem_map_dma_buf<\/td>\nobj->funcs->get_sg_table<\/td>\n<\/tr>\n
    unmap_dma_buf<\/td>\ndrm_gem_unmap_dma_buf<\/td>\n\u2014\u2014<\/td>\n<\/tr>\n
    release<\/td>\ndrm_gem_dmabuf_release<\/td>\nobj \u5f15\u7528\u91ca\u653e<\/td>\n<\/tr>\n
    mmap<\/td>\ndrm_gem_dmabuf_mmap<\/td>\nobj->funcs->mmap<\/td>\n<\/tr>\n
    vmap \/ vunmap<\/td>\ndrm_gem_dmabuf_vmap<\/td>\nobj->funcs->vmap<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    dma-buf core \u901a\u8fc7 drm_gem_prime_dmabuf_ops \u6572\u95e8，\u6700\u7ec8\u90fd\u843d\u5230\u67d0\u4e2a drm_gem_object_funcs \u4e0a\u3002\u8fd9\u4e5f\u89e3\u91ca\u4e86 5.2.4 \u91cc amdgpu \u7684 map_dma_buf \u4e3a\u4f55\u6700\u7ec8\u4f1a\u8d70\u5230 GEM \u7684 get_sg_table\u2014\u2014\u4e2d\u95f4\u6b63\u662f\u8fd9\u5f20\u8f6c\u63a5\u8868\u5728\u7275\u7ebf\u3002\u82e5\u9a71\u52a8\u7684 get_sg_table \u672a\u5b9e\u73b0，drm_gem_map_attach \u4f1a\u76f4\u63a5\u8fd4\u56de -ENOSYS，\u5373\u62d2\u7edd\u5bfc\u51fa\u5230\u522b\u7684\u8bbe\u5907\u3002<\/p>\n

    3. \u5bfc\u5165\u6865：fd \u2192 handle<\/h3>\n

    \u53cd\u65b9\u5411\u7684 drm_gem_prime_fd_to_handle() \u8981\u628a\u4e00\u679a\u964c\u751f\u7684 fd \u53d8\u6210\u672c\u8fdb\u7a0b\u7684 handle：<\/p>\n

    int<\/span> drm_gem_prime_fd_to_handle<\/span>(<\/span>struct<\/span> drm_device<\/span> *<\/span>dev,<\/span> struct<\/span> drm_file<\/span> *<\/span>file_priv,<\/span>
    \n int<\/span> prime_fd,<\/span> uint32_t<\/span> *<\/span>handle)<\/span>
    \n{<\/span>
    \n struct<\/span> dma_buf<\/span> *<\/span>dma_buf =<\/span> dma_buf_get<\/span>(<\/span>prime_fd)<\/span>;<\/span> \/* fd \u2192 struct dma_buf *\/<\/span>
    \n .<\/span>.<\/span>.<\/span>
    \n \/* 1. \u67e5\u672c\u8fdb\u7a0b\u7684\u5bfc\u5165\u7f13\u5b58：\u8fd9\u4e2a dma_buf \u4e4b\u524d\u5bfc\u5165\u8fc7\u5417？ *\/<\/span>
    \n ret =<\/span> drm_prime_lookup_buf_handle<\/span>(<\/span>&<\/span>file_priv-><\/span>prime,<\/span> dma_buf,<\/span> handle)<\/span>;<\/span>
    \n if<\/span> (<\/span>ret ==<\/span> 0<\/span>)<\/span>
    \n goto<\/span> out_put;<\/span> \/* \u547d\u4e2d \u2192 \u590d\u7528\u65e7 handle *\/<\/span><\/p>\n

    \/* 2. \u6ca1\u89c1\u8fc7 \u2192 \u8c03\u9a71\u52a8\u7684 import \u56de\u8c03，\u9020\u4e00\u4e2a GEM \u5bf9\u8c61 *\/<\/span>
    \n if<\/span> (<\/span>dev-><\/span>driver-><\/span>gem_prime_import)<\/span>
    \n obj =<\/span> dev-><\/span>driver-><\/span>gem_prime_import<\/span>(<\/span>dev,<\/span> dma_buf)<\/span>;<\/span>
    \n else<\/span>
    \n obj =<\/span> drm_gem_prime_import<\/span>(<\/span>dev,<\/span> dma_buf)<\/span>;<\/span>
    \n .<\/span>.<\/span>.<\/span>
    \n \/* 3. \u5efa\u7acb GEM \u5bf9\u8c61 \u2194 dma_buf \u7684\u53cc\u5411\u5f15\u7528 *\/<\/span>
    \n if<\/span> (<\/span>!<\/span>obj-><\/span>dma_buf)<\/span> {<\/span>
    \n obj-><\/span>dma_buf =<\/span> dma_buf;<\/span>
    \n get_dma_buf<\/span>(<\/span>dma_buf)<\/span>;<\/span>
    \n }<\/span><\/p>\n

    \/* 4. \u4e3a\u8fd9\u4e2a GEM \u5bf9\u8c61\u5206\u914d\u672c\u8fdb\u7a0b handle，\u5e76\u5199\u5165\u7f13\u5b58 *\/<\/span>
    \n ret =<\/span> drm_gem_handle_create_tail<\/span>(<\/span>file_priv,<\/span> obj,<\/span> handle)<\/span>;<\/span>
    \n ret =<\/span> drm_prime_add_buf_handle<\/span>(<\/span>&<\/span>file_priv-><\/span>prime,<\/span> dma_buf,<\/span> *<\/span>handle)<\/span>;<\/span>
    \n .<\/span>.<\/span>.<\/span>
    \n}<\/span><\/p>\n

    \u5173\u952e\u4ecd\u662f\u7f13\u5b58 + \u552f\u4e00\u6027：file_priv->prime \u662f\u6bcf\u4e2a DRM file \u79c1\u6709\u7684\u53cc\u5411\u7f13\u5b58（dma_buf \u2194 handle）\u3002\u540c\u4e00\u4e2a dma_buf \u5728\u540c\u4e00\u8fdb\u7a0b\u88ab\u5bfc\u5165\u4e24\u6b21，\u7b2c 1 \u6b65\u5c31\u4f1a\u547d\u4e2d\u7f13\u5b58\u8fd4\u56de\u540c\u4e00\u4e2a handle\u2014\u2014\u4fdd\u8bc1\u300c\u4e00\u5757\u5171\u4eab buffer \u5728\u4e00\u4e2a\u8fdb\u7a0b\u91cc\u53ea\u6709\u4e00\u4e2a handle\u300d\u3002<\/p>\n

    \u7b2c 2 \u6b65\u7684 drm_gem_prime_import() \u8f6c\u8c03\u6838\u5fc3\u7684 drm_gem_prime_import_dev()，\u5b83\u624d\u662f\u771f\u6b63\u300c\u628a dma_buf \u53d8\u6210 GEM \u5bf9\u8c61\u300d\u7684\u5730\u65b9，\u5176\u4e2d\u85cf\u7740\u4e00\u4e2a\u91cd\u8981\u4f18\u5316：<\/p>\n

    struct<\/span> drm_gem_object<\/span> *<\/span>drm_gem_prime_import_dev<\/span>(<\/span>struct<\/span> drm_device<\/span> *<\/span>dev,<\/span>
    \n struct<\/span> dma_buf<\/span> *<\/span>dma_buf,<\/span> struct<\/span> device<\/span> *<\/span>attach_dev)<\/span>
    \n{<\/span>
    \n \/* \u81ea\u5bfc\u5165\u4f18\u5316：\u5982\u679c\u8fd9\u4e2a dma_buf \u6b63\u662f\u672c dev \u81ea\u5df1\u5bfc\u51fa\u7684，
    \n * \u4e0d\u5fc5 attach，\u76f4\u63a5\u7ed9\u539f GEM \u5bf9\u8c61\u52a0\u5f15\u7528\u5373\u53ef *\/<\/span>
    \n if<\/span> (<\/span>drm_gem_is_prime_exported_dma_buf<\/span>(<\/span>dev,<\/span> dma_buf)<\/span>)<\/span> {<\/span>
    \n obj =<\/span> dma_buf-><\/span>priv;<\/span>
    \n drm_gem_object_get<\/span>(<\/span>obj)<\/span>;<\/span>
    \n return<\/span> obj;<\/span>
    \n }<\/span><\/p>\n

    if<\/span> (<\/span>!<\/span>dev-><\/span>driver-><\/span>gem_prime_import_sg_table)<\/span>
    \n return<\/span> ERR_PTR<\/span>(<\/span>–<\/span>EINVAL)<\/span>;<\/span><\/p>\n

    \/* \u6b63\u5e38\u8def\u5f84：attach \u2192 map \u62ff sg_table \u2192 \u8ba9\u9a71\u52a8\u636e\u6b64\u9020 GEM \u5bf9\u8c61 *\/<\/span>
    \n attach =<\/span> dma_buf_attach<\/span>(<\/span>dma_buf,<\/span> attach_dev)<\/span>;<\/span>
    \n get_dma_buf<\/span>(<\/span>dma_buf)<\/span>;<\/span>
    \n sgt =<\/span> dma_buf_map_attachment_unlocked<\/span>(<\/span>attach,<\/span> DMA_BIDIRECTIONAL)<\/span>;<\/span>
    \n obj =<\/span> dev-><\/span>driver-><\/span>gem_prime_import_sg_table<\/span>(<\/span>dev,<\/span> attach,<\/span> sgt)<\/span>;<\/span> \/* \u9a71\u52a8\u56de\u8c03 *\/<\/span><\/p>\n

    obj-><\/span>import_attach =<\/span> attach;<\/span> \/* \u8bb0\u4f4f\u300c\u6211\u662f\u5bfc\u5165\u6765\u7684\u300d\u53ca\u5176 attachment *\/<\/span>
    \n obj-><\/span>resv =<\/span> dma_buf-><\/span>resv;<\/span> \/* \u5171\u7528\u6e90 dma-buf \u7684 resv \u2192 \u540c\u6b65\u80fd\u8de8\u8bbe\u5907\u751f\u6548 *\/<\/span>
    \n return<\/span> obj;<\/span>
    \n}<\/span><\/p>\n

    \u4e09\u4e2a\u8981\u70b9\u4e32\u8d77\u4e86\u524d\u51e0\u8282：<\/p>\n

  • \u81ea\u5bfc\u5165\u4f18\u5316（drm_gem_is_prime_exported_dma_buf）：\u628a\u81ea\u5df1\u5bfc\u51fa\u7684 dma-buf \u518d\u5bfc\u5165\u56de\u6765，\u53ea\u589e\u52a0 GEM \u5bf9\u8c61\u5f15\u7528\u3001\u4e0d\u589e\u52a0 dma-buf \u7684 f_count\u2014\u2014\u907f\u514d\u81ea\u5df1 attach \u81ea\u5df1\u7684\u75c5\u6001\u5faa\u73af\u3002\u8fd9\u4e0e\u7b2c 2 \u8282\u5bfc\u51fa\u4fa7\u300c\u60c5\u51b5\u4e00\u300d\u4e92\u4e3a\u955c\u50cf\u3002<\/li>\n
  • attach + map \u590d\u7528 5.2.4 \u7684\u673a\u5236：\u5bfc\u5165\u6865\u5e76\u4e0d\u81ea\u5df1\u53d1\u660e\u8f6e\u5b50，\u800c\u662f\u8001\u8001\u5b9e\u5b9e\u8d70 dma_buf_attach \u2192 dma_buf_map_attachment \u62ff\u5230 sg_table，\u518d\u4ea4\u7ed9\u9a71\u52a8\u7684 gem_prime_import_sg_table \u636e\u6b64\u6784\u9020\u4e00\u4e2a\u300c\u5f71\u5b50 GEM \u5bf9\u8c61\u300d\u3002<\/li>\n
  • import_attach + \u5171\u7528 resv：obj->import_attach \u6807\u8bb0\u8fd9\u662f\u5bfc\u5165\u5bf9\u8c61（\u7b2c 2 \u8282\u5bfc\u51fa\u4fa7\u636e\u6b64\u590d\u7528\u539f\u59cb dma-buf）；obj->resv = dma_buf->resv \u8ba9\u5f71\u5b50\u5bf9\u8c61\u4e0e\u6e90 buffer \u5171\u4eab fence \u5bb9\u5668\u2014\u2014\u8fd9\u662f\u8de8\u8bbe\u5907\u9690\u5f0f\u540c\u6b65（6.3）\u6210\u7acb\u7684\u524d\u63d0\u3002\u9a71\u52a8\u8fd8\u987b\u5728\u5176 free \u56de\u8c03\u91cc\u8c03 drm_prime_gem_destroy() \u6536\u5c3e attach\u3002<\/li>\n

    4. \u4e00\u5f20\u5168\u666f\u56fe：\u4e24\u5957\u5bf9\u8c61\u6a21\u578b\u5982\u4f55\u5bf9\u9f50<\/h3>\n

    \u628a\u5bfc\u51fa\u4e0e\u5bfc\u5165\u5408\u8d77\u6765\u770b，PRIME \u7684\u672c\u8d28\u662f\u7ef4\u62a4\u300cGEM \u5bf9\u8c61 \u2194 dma_buf\u300d\u7684\u4e00\u4e00\u5bf9\u5e94\u4e0e\u5f15\u7528\u8ba1\u6570：<\/p>\n

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    <\/p>\n

    dma-buf \u4e16\u754c<\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    GEM \u4e16\u754c<\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    export: funcs->export \/ drm_gem_prime_export<\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    import: gem_prime_import_sg_table<\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    handle \u2194 dma_buf \u7f13\u5b58（file_priv->prime）<\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    fd \u2194 handle<\/p>\n

    <\/span><\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    drm_gem_objectobj->dma_buf（\u7f13\u5b58）obj->import_attach（\u82e5\u5bfc\u5165）obj->resv<\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    struct dma_bufdma_buf->priv = objdma_buf->ops = drm_gem_prime_dmabuf_opsdma_buf->resv = obj->resv<\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    \u8fdb\u7a0b\u5185 handle<\/p>\n

    <\/span><\/p>\n

    <\/p>\n

    \u8de8\u8fdb\u7a0b fd<\/p>\n

    <\/span><\/p>\n

      \n
    • priv \/ dma_buf \u4e92\u6307：dma_buf \u7528 priv \u6307\u56de GEM \u5bf9\u8c61，GEM \u5bf9\u8c61\u7528 dma_buf \u7f13\u5b58\u53cd\u5411\u5f15\u7528，\u4e8c\u8005\u4e00\u4e00\u5bf9\u5e94\u3002<\/li>\n
    • resv \u5171\u7528：\u5bfc\u51fa\u65f6 dma_buf->resv = obj->resv，\u5bfc\u5165\u65f6 obj->resv = dma_buf->resv，\u6700\u7ec8\u8de8\u8bbe\u5907\u7684\u4e24\u4e2a GEM \u5f71\u5b50\u5bf9\u8c61\u5171\u4eab\u540c\u4e00\u4e2a dma_resv\u2014\u2014\u540c\u6b65\u8bed\u4e49\u5f97\u4ee5\u8d2f\u901a\u3002<\/li>\n
    • \u4e24\u7ea7\u7f13\u5b58：file_priv->prime \u7ba1\u300cfd\/dma_buf \u2194 handle\u300d，obj->dma_buf \u7ba1\u300cGEM \u5bf9\u8c61 \u2194 dma_buf\u300d，\u5171\u540c\u4fdd\u8bc1\u4efb\u4f55\u4e00\u5757\u5171\u4eab buffer \u5728\u4efb\u4e00\u8fdb\u7a0b\u3001\u4efb\u4e00\u65b9\u5411\u90fd\u4e0d\u4f1a\u5206\u88c2\u51fa\u591a\u4e2a\u526f\u672c\u3002<\/li>\n<\/ul>\n

      5. \u5c0f\u7ed3\u4e0e\u5ef6\u4f38<\/h3>\n
    • PRIME \u662f GEM \u4e0e dma-buf \u4e4b\u95f4\u7684\u53cc\u5411\u6865：HANDLE_TO_FD \u5bfc\u51fa\u3001FD_TO_HANDLE \u5bfc\u5165，\u628a\u300c\u8fdb\u7a0b\u79c1\u6709 handle\u300d\u4e0e\u300c\u53ef\u4f20\u9012 fd\u300d\u4e92\u76f8\u7ffb\u8bd1\u3002<\/li>\n
    • drm_gem_prime_dmabuf_ops \u662f\u8f6c\u63a5\u8868：dma-buf \u7684\u901a\u7528\u56de\u8c03（attach\/map\/mmap\/vmap）\u7ecf\u5b83\u7edf\u4e00\u843d\u5230 GEM \u7684 drm_gem_object_funcs，map_dma_buf \u6700\u7ec8\u59d4\u6d3e get_sg_table\u2014\u2014\u8fd9\u6b63\u662f 5.2.4 amdgpu \u90a3\u6761\u56de\u8c03\u94fe\u7684\u4e2d\u67a2\u3002<\/li>\n
    • \u552f\u4e00\u6027\u4e0e\u5f15\u7528\u8ba1\u6570\u662f\u7075\u9b42：obj->dma_buf \u7f13\u5b58\u3001import_attach \u590d\u7528\u3001file_priv->prime \u53cc\u5411\u7f13\u5b58\u3001\u81ea\u5bfc\u5165\u4f18\u5316\u3001\u5171\u7528 resv，\u4e94\u6761\u673a\u5236\u5171\u540c\u4fdd\u8bc1\u300c\u4e00\u5757 buffer \u5728\u4e00\u4e2a\u8fdb\u7a0b\u91cc\u53ea\u6709\u4e00\u4e2a handle\u3001\u4e00\u4e2a GEM \u5bf9\u8c61\u53ea\u5bf9\u5e94\u4e00\u4e2a dma_buf\u300d\u3002<\/li>\n

      \u5230\u8fd9\u91cc，PRIME \u7684\u6838\u5fc3\u6865\u63a5\u5df2\u7ecf\u6e05\u6670，\u4f46\u8fd8\u6709\u4e00\u4e2a\u5b9e\u9645\u95ee\u9898：gem_prime_import_sg_table\u3001get_sg_table\u3001pin\/unpin \u8fd9\u4e9b\u56de\u8c03，\u666e\u901a\u9a71\u52a8\u8981\u4e0d\u8981\u6bcf\u4e2a\u90fd\u81ea\u5df1\u5199\u4e00\u904d？\u5bf9\u5927\u91cf\u57fa\u4e8e\u7cfb\u7edf\u5185\u5b58\u7684\u7b80\u5355\u9a71\u52a8，DRM \u63d0\u4f9b\u4e86\u5f00\u7bb1\u5373\u7528\u7684 GEM shmem helper，\u628a\u8fd9\u5957\u5171\u4eab\u8def\u5f84\u5168\u90e8\u5b9e\u73b0\u597d\u4e86\u3002\u8fd9\u6b63\u662f [5.3.2 GEM shmem helper \u7684\u5171\u4eab\u8def\u5f84] \u7684\u4e3b\u9898\u3002<\/p>\n

      \u76f8\u5173\u9605\u8bfb：dma-buf \u7684 attach\/map \u673a\u5236\u89c1 5.2.4；get_sg_table \/ pin \/ unpin \u7b49 GEM \u56de\u8c03\u7684\u8bed\u4e49\u89c1 gem_object_funcs.md；\u5171\u7528 resv \u5e26\u6765\u7684\u9690\u5f0f\u540c\u6b65\u89c1 6.3 dma_resv\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

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