/* * GK20A memory management * * Copyright (c) 2011-2017, NVIDIA CORPORATION. All rights reserved. * * This program is free software; you can redistribute it and/or modify it * under the terms and conditions of the GNU General Public License, * version 2, as published by the Free Software Foundation. * * This program is distributed in the hope it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ #ifndef MM_GK20A_H #define MM_GK20A_H #include #include #include #include #include #include #include #include #include #ifdef CONFIG_ARM64 #define outer_flush_range(a, b) #define __cpuc_flush_dcache_area __flush_dcache_area #endif #define FLUSH_CPU_DCACHE(va, pa, size) \ do { \ __cpuc_flush_dcache_area((void *)(va), (size_t)(size)); \ outer_flush_range(pa, pa + (size_t)(size)); \ } while (0) enum gk20a_mem_rw_flag { gk20a_mem_flag_none = 0, gk20a_mem_flag_read_only = 1, gk20a_mem_flag_write_only = 2, }; struct gpfifo_desc { struct mem_desc mem; u32 entry_num; u32 get; u32 put; bool wrap; /* if gpfifo lives in vidmem or is forced to go via PRAMIN, first copy * from userspace to pipe and then from pipe to gpu buffer */ void *pipe; }; struct patch_desc { struct mem_desc mem; u32 data_count; }; struct zcull_ctx_desc { u64 gpu_va; u32 ctx_attr; u32 ctx_sw_mode; }; struct pm_ctx_desc { struct mem_desc mem; u32 pm_mode; }; struct gk20a; struct compbit_store_desc { struct mem_desc mem; /* The value that is written to the hardware. This depends on * on the number of ltcs and is not an address. */ u64 base_hw; }; struct gk20a_buffer_state { struct list_head list; /* The valid compbits and the fence must be changed atomically. */ struct nvgpu_mutex lock; /* Offset of the surface within the dma-buf whose state is * described by this struct (one dma-buf can contain multiple * surfaces with different states). */ size_t offset; /* A bitmask of valid sets of compbits (0 = uncompressed). */ u32 valid_compbits; /* The ZBC color used on this buffer. */ u32 zbc_color; /* This struct reflects the state of the buffer when this * fence signals. */ struct gk20a_fence *fence; }; enum gmmu_pgsz_gk20a { gmmu_page_size_small = 0, gmmu_page_size_big = 1, gmmu_page_size_kernel = 2, gmmu_nr_page_sizes = 3, }; struct gk20a_comptags { u32 offset; u32 lines; u32 allocated_lines; bool user_mappable; }; struct gk20a_mm_entry { /* backing for */ struct mem_desc mem; u32 woffset; /* if >0, mem is a shadow copy, owned by another entry */ int pgsz; struct gk20a_mm_entry *entries; int num_entries; }; struct priv_cmd_queue { struct mem_desc mem; u32 size; /* num of entries in words */ u32 put; /* put for priv cmd queue */ u32 get; /* get for priv cmd queue */ }; struct priv_cmd_entry { bool valid; struct mem_desc *mem; u32 off; /* offset in mem, in u32 entries */ u64 gva; u32 get; /* start of entry in queue */ u32 size; /* in words */ struct list_head list; /* node for lists */ }; struct mapped_buffer_node { struct vm_gk20a *vm; struct nvgpu_rbtree_node node; struct list_head unmap_list; struct nvgpu_list_node va_buffers_list; struct vm_reserved_va_node *va_node; u64 addr; u64 size; struct dma_buf *dmabuf; struct sg_table *sgt; struct kref ref; u32 user_mapped; bool own_mem_ref; u32 pgsz_idx; u32 ctag_offset; u32 ctag_lines; u32 ctag_allocated_lines; /* For comptag mapping, these are the mapping window parameters */ bool ctags_mappable; u64 ctag_map_win_addr; /* non-zero if mapped */ u64 ctag_map_win_size; /* non-zero if ctags_mappable */ u32 ctag_map_win_ctagline; /* ctagline at win start, set if * ctags_mappable */ u32 flags; u32 kind; bool va_allocated; }; static inline struct mapped_buffer_node * mapped_buffer_node_from_va_buffers_list(struct nvgpu_list_node *node) { return (struct mapped_buffer_node *) ((uintptr_t)node - offsetof(struct mapped_buffer_node, va_buffers_list)); }; static inline struct mapped_buffer_node * mapped_buffer_from_rbtree_node(struct nvgpu_rbtree_node *node) { return (struct mapped_buffer_node *) ((uintptr_t)node - offsetof(struct mapped_buffer_node, node)); }; struct vm_reserved_va_node { struct nvgpu_list_node reserved_va_list; struct nvgpu_list_node va_buffers_list; u32 pgsz_idx; u64 vaddr_start; u64 size; bool sparse; }; static inline struct vm_reserved_va_node * vm_reserved_va_node_from_reserved_va_list(struct nvgpu_list_node *node) { return (struct vm_reserved_va_node *) ((uintptr_t)node - offsetof(struct vm_reserved_va_node, reserved_va_list)); }; struct gk20a_mmu_level { int hi_bit[2]; int lo_bit[2]; int (*update_entry)(struct vm_gk20a *vm, struct gk20a_mm_entry *pte, u32 i, u32 gmmu_pgsz_idx, struct scatterlist **sgl, u64 *offset, u64 *iova, u32 kind_v, u64 *ctag, bool cacheable, bool unmapped_pte, int rw_flag, bool sparse, bool priv, enum nvgpu_aperture aperture); size_t entry_size; }; /* map/unmap batch state */ struct vm_gk20a_mapping_batch { bool gpu_l2_flushed; bool need_tlb_invalidate; }; struct vm_gk20a { struct mm_gk20a *mm; struct gk20a_as_share *as_share; /* as_share this represents */ u64 va_start; u64 va_limit; int num_user_mapped_buffers; bool big_pages; /* enable large page support */ bool enable_ctag; bool mapped; u32 big_page_size; bool userspace_managed; const struct gk20a_mmu_level *mmu_levels; struct kref ref; struct nvgpu_mutex update_gmmu_lock; struct gk20a_mm_entry pdb; /* * These structs define the address spaces. In some cases it's possible * to merge address spaces (user and user_lp) and in other cases it's * not. vma[] allows the code to be agnostic to this by always using * address spaces through this pointer array. */ struct nvgpu_allocator *vma[gmmu_nr_page_sizes]; struct nvgpu_allocator kernel; struct nvgpu_allocator user; struct nvgpu_allocator user_lp; struct nvgpu_rbtree_node *mapped_buffers; struct nvgpu_list_node reserved_va_list; #ifdef CONFIG_TEGRA_GR_VIRTUALIZATION u64 handle; #endif u32 gmmu_page_sizes[gmmu_nr_page_sizes]; /* if non-NULL, kref_put will use this batch when unmapping. Must hold vm->update_gmmu_lock. */ struct vm_gk20a_mapping_batch *kref_put_batch; /* * Each address space needs to have a semaphore pool. */ struct nvgpu_semaphore_pool *sema_pool; }; struct gk20a; struct channel_gk20a; int gk20a_init_mm_support(struct gk20a *g); int gk20a_init_mm_setup_sw(struct gk20a *g); int gk20a_init_mm_setup_hw(struct gk20a *g); void gk20a_mm_debugfs_init(struct device *dev); void gk20a_init_mm_ce_context(struct gk20a *g); int gk20a_mm_fb_flush(struct gk20a *g); void gk20a_mm_l2_flush(struct gk20a *g, bool invalidate); void gk20a_mm_cbc_clean(struct gk20a *g); void gk20a_mm_l2_invalidate(struct gk20a *g); struct mmu_fault_info { u64 inst_ptr; u32 inst_aperture; u64 fault_addr; u32 fault_addr_aperture; u32 timestamp_lo; u32 timestamp_hi; u32 mmu_engine_id; u32 gpc_id; u32 client_type; u32 client_id; u32 fault_type; u32 access_type; u32 protected_mode; u32 replayable_fault; u32 replay_fault_en; u32 valid; u32 faulted_pbdma; u32 faulted_engine; u32 hw_chid; struct channel_gk20a *refch; }; struct mm_gk20a { struct gk20a *g; /* GPU VA default sizes address spaces for channels */ struct { u64 user_size; /* userspace-visible GPU VA region */ u64 kernel_size; /* kernel-only GPU VA region */ } channel; struct { u32 aperture_size; struct vm_gk20a vm; struct mem_desc inst_block; } bar1; struct { u32 aperture_size; struct vm_gk20a vm; struct mem_desc inst_block; } bar2; struct { u32 aperture_size; struct vm_gk20a vm; struct mem_desc inst_block; } pmu; struct { /* using pmu vm currently */ struct mem_desc inst_block; } hwpm; struct { struct vm_gk20a vm; } cde; struct { struct vm_gk20a vm; } ce; struct nvgpu_mutex l2_op_lock; struct nvgpu_mutex tlb_lock; struct nvgpu_mutex priv_lock; #ifdef CONFIG_ARCH_TEGRA_18x_SOC struct mem_desc bar2_desc; #endif /* * Separate function to cleanup the CE since it requires a channel to * be closed which must happen before fifo cleanup. */ void (*remove_ce_support)(struct mm_gk20a *mm); void (*remove_support)(struct mm_gk20a *mm); bool sw_ready; int physical_bits; bool use_full_comp_tag_line; #ifdef CONFIG_DEBUG_FS u32 ltc_enabled; #if LINUX_VERSION_CODE < KERNEL_VERSION(4,4,0) u32 ltc_enabled_debug; #else bool ltc_enabled_debug; #endif #endif #if LINUX_VERSION_CODE < KERNEL_VERSION(4,4,0) u32 bypass_smmu; u32 disable_bigpage; #else bool bypass_smmu; bool disable_bigpage; #endif bool has_physical_mode; /* false if vidmem aperture actually points to sysmem */ bool vidmem_is_vidmem; struct mem_desc sysmem_flush; u32 pramin_window; struct nvgpu_spinlock pramin_window_lock; #if LINUX_VERSION_CODE < KERNEL_VERSION(4,4,0) u32 force_pramin; /* via debugfs */ #else bool force_pramin; /* via debugfs */ #endif struct { size_t size; u64 base; size_t bootstrap_size; u64 bootstrap_base; struct nvgpu_allocator allocator; struct nvgpu_allocator bootstrap_allocator; u32 ce_ctx_id; volatile bool cleared; struct nvgpu_mutex first_clear_mutex; struct nvgpu_list_node clear_list_head; struct nvgpu_mutex clear_list_mutex; struct work_struct clear_mem_worker; atomic64_t bytes_pending; } vidmem; }; int gk20a_mm_init(struct mm_gk20a *mm); #define gk20a_from_mm(mm) ((mm)->g) #define gk20a_from_vm(vm) ((vm)->mm->g) #define dev_from_vm(vm) dev_from_gk20a(vm->mm->g) #define DEFAULT_ALLOC_ALIGNMENT (4*1024) static inline int bar1_aperture_size_mb_gk20a(void) { return 16; /* 16MB is more than enough atm. */ } /* The maximum GPU VA range supported */ #define NV_GMMU_VA_RANGE 38 /* The default userspace-visible GPU VA size */ #define NV_MM_DEFAULT_USER_SIZE (1ULL << 37) /* The default kernel-reserved GPU VA size */ #define NV_MM_DEFAULT_KERNEL_SIZE (1ULL << 32) /* * When not using unified address spaces the bottom 16GB of the space are used * for small pages and the remaining high memory is used for large pages. */ static inline u64 __nv_gmmu_va_small_page_limit(void) { return ((u64)SZ_1G * 16); } enum gmmu_pgsz_gk20a __get_pte_size_fixed_map(struct vm_gk20a *vm, u64 base, u64 size); enum gmmu_pgsz_gk20a __get_pte_size(struct vm_gk20a *vm, u64 base, u64 size); void set_vidmem_page_alloc(struct scatterlist *sgl, u64 addr); bool is_vidmem_page_alloc(u64 addr); struct nvgpu_page_alloc *get_vidmem_page_alloc(struct scatterlist *sgl); #if 0 /*related to addr bits above, concern below TBD on which is accurate */ #define bar1_instance_block_shift_gk20a() (max_physaddr_bits_gk20a() -\ bus_bar1_block_ptr_s()) #else #define bar1_instance_block_shift_gk20a() bus_bar1_block_ptr_shift_v() #endif int gk20a_alloc_inst_block(struct gk20a *g, struct mem_desc *inst_block); void gk20a_free_inst_block(struct gk20a *g, struct mem_desc *inst_block); void gk20a_init_inst_block(struct mem_desc *inst_block, struct vm_gk20a *vm, u32 big_page_size); u64 gk20a_mm_inst_block_addr(struct gk20a *g, struct mem_desc *mem); void gk20a_mm_dump_vm(struct vm_gk20a *vm, u64 va_begin, u64 va_end, char *label); int gk20a_mm_suspend(struct gk20a *g); int gk20a_get_sgtable(struct device *d, struct sg_table **sgt, void *cpuva, u64 iova, size_t size); int gk20a_get_sgtable_from_pages(struct device *d, struct sg_table **sgt, struct page **pages, u64 iova, size_t size); void gk20a_free_sgtable(struct gk20a *g, struct sg_table **sgt); u64 gk20a_mm_iova_addr(struct gk20a *g, struct scatterlist *sgl, u32 flags); u64 gk20a_mm_smmu_vaddr_translate(struct gk20a *g, dma_addr_t iova); u64 gk20a_mem_get_base_addr(struct gk20a *g, struct mem_desc *mem, u32 flags); void gk20a_mm_ltc_isr(struct gk20a *g); bool gk20a_mm_mmu_debug_mode_enabled(struct gk20a *g); int gk20a_mm_mmu_vpr_info_fetch(struct gk20a *g); u64 gk20a_gmmu_map(struct vm_gk20a *vm, struct sg_table **sgt, u64 size, u32 flags, int rw_flag, bool priv, enum nvgpu_aperture aperture); u64 gk20a_gmmu_fixed_map(struct vm_gk20a *vm, struct sg_table **sgt, u64 addr, u64 size, u32 flags, int rw_flag, bool priv, enum nvgpu_aperture aperture); /* Flags for the below gk20a_gmmu_{alloc,alloc_map}_flags* */ /* * Don't create a virtual kernel mapping for the buffer but only allocate it; * this may save some resources. The buffer can be mapped later explicitly. */ #define NVGPU_DMA_NO_KERNEL_MAPPING (1 << 0) /* * Don't allow building the buffer from individual pages but require a * physically contiguous block. */ #define NVGPU_DMA_FORCE_CONTIGUOUS (1 << 1) /* * Make the mapping read-only. */ #define NVGPU_DMA_READ_ONLY (1 << 2) int gk20a_gmmu_alloc_map(struct vm_gk20a *vm, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_map_flags(struct vm_gk20a *vm, unsigned long flags, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_map_sys(struct vm_gk20a *vm, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_map_flags_sys(struct vm_gk20a *vm, unsigned long flags, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_map_vid(struct vm_gk20a *vm, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_map_flags_vid(struct vm_gk20a *vm, unsigned long flags, size_t size, struct mem_desc *mem); void gk20a_gmmu_unmap_free(struct vm_gk20a *vm, struct mem_desc *mem); int gk20a_gmmu_alloc(struct gk20a *g, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_flags(struct gk20a *g, unsigned long flags, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_sys(struct gk20a *g, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_flags_sys(struct gk20a *g, unsigned long flags, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_vid(struct gk20a *g, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_flags_vid(struct gk20a *g, unsigned long flags, size_t size, struct mem_desc *mem); int gk20a_gmmu_alloc_flags_vid_at(struct gk20a *g, unsigned long flags, size_t size, struct mem_desc *mem, dma_addr_t at); void gk20a_gmmu_free(struct gk20a *g, struct mem_desc *mem); static inline phys_addr_t gk20a_mem_phys(struct mem_desc *mem) { /* FIXME: the sgt/sgl may get null if this is accessed e.g. in an isr * during channel deletion - attempt to fix at least null derefs */ struct sg_table *sgt = mem->sgt; if (sgt) { struct scatterlist *sgl = sgt->sgl; if (sgl) return sg_phys(sgl); } return 0; } u32 __nvgpu_aperture_mask(struct gk20a *g, enum nvgpu_aperture aperture, u32 sysmem_mask, u32 vidmem_mask); u32 nvgpu_aperture_mask(struct gk20a *g, struct mem_desc *mem, u32 sysmem_mask, u32 vidmem_mask); void gk20a_pde_wr32(struct gk20a *g, struct gk20a_mm_entry *entry, size_t w, size_t data); u64 gk20a_pde_addr(struct gk20a *g, struct gk20a_mm_entry *entry); u64 gk20a_locked_gmmu_map(struct vm_gk20a *vm, u64 map_offset, struct sg_table *sgt, u64 buffer_offset, u64 size, int pgsz_idx, u8 kind_v, u32 ctag_offset, u32 flags, int rw_flag, bool clear_ctags, bool sparse, bool priv, struct vm_gk20a_mapping_batch *batch, enum nvgpu_aperture aperture); void gk20a_gmmu_unmap(struct vm_gk20a *vm, u64 vaddr, u64 size, int rw_flag); void gk20a_locked_gmmu_unmap(struct vm_gk20a *vm, u64 vaddr, u64 size, int pgsz_idx, bool va_allocated, int rw_flag, bool sparse, struct vm_gk20a_mapping_batch *batch); struct sg_table *gk20a_mm_pin(struct device *dev, struct dma_buf *dmabuf); void gk20a_mm_unpin(struct device *dev, struct dma_buf *dmabuf, struct sg_table *sgt); u64 gk20a_vm_map(struct vm_gk20a *vm, struct dma_buf *dmabuf, u64 offset_align, u32 flags /*NVGPU_AS_MAP_BUFFER_FLAGS_*/, int kind, struct sg_table **sgt, bool user_mapped, int rw_flag, u64 buffer_offset, u64 mapping_size, struct vm_gk20a_mapping_batch *mapping_batch); int gk20a_vm_get_compbits_info(struct vm_gk20a *vm, u64 mapping_gva, u64 *compbits_win_size, u32 *compbits_win_ctagline, u32 *mapping_ctagline, u32 *flags); int gk20a_vm_map_compbits(struct vm_gk20a *vm, u64 mapping_gva, u64 *compbits_win_gva, u64 *mapping_iova, u32 flags); /* unmap handle from kernel */ void gk20a_vm_unmap(struct vm_gk20a *vm, u64 offset); void gk20a_vm_unmap_locked(struct mapped_buffer_node *mapped_buffer, struct vm_gk20a_mapping_batch *batch); /* get reference to all currently mapped buffers */ int gk20a_vm_get_buffers(struct vm_gk20a *vm, struct mapped_buffer_node ***mapped_buffers, int *num_buffers); /* put references on the given buffers */ void gk20a_vm_put_buffers(struct vm_gk20a *vm, struct mapped_buffer_node **mapped_buffers, int num_buffers); /* find buffer corresponding to va */ int gk20a_vm_find_buffer(struct vm_gk20a *vm, u64 gpu_va, struct dma_buf **dmabuf, u64 *offset); void gk20a_vm_get(struct vm_gk20a *vm); void gk20a_vm_put(struct vm_gk20a *vm); void gk20a_vm_remove_support(struct vm_gk20a *vm); u64 gk20a_vm_alloc_va(struct vm_gk20a *vm, u64 size, enum gmmu_pgsz_gk20a gmmu_pgsz_idx); int gk20a_vm_free_va(struct vm_gk20a *vm, u64 offset, u64 size, enum gmmu_pgsz_gk20a pgsz_idx); /* vm-as interface */ struct nvgpu_as_alloc_space_args; struct nvgpu_as_free_space_args; int gk20a_vm_alloc_share(struct gk20a_as_share *as_share, u32 big_page_size, u32 flags); int gk20a_vm_release_share(struct gk20a_as_share *as_share); int gk20a_vm_alloc_space(struct gk20a_as_share *as_share, struct nvgpu_as_alloc_space_args *args); int gk20a_vm_free_space(struct gk20a_as_share *as_share, struct nvgpu_as_free_space_args *args); int gk20a_vm_bind_channel(struct gk20a_as_share *as_share, struct channel_gk20a *ch); int __gk20a_vm_bind_channel(struct vm_gk20a *vm, struct channel_gk20a *ch); /* batching eliminates redundant cache flushes and invalidates */ void gk20a_vm_mapping_batch_start(struct vm_gk20a_mapping_batch *batch); void gk20a_vm_mapping_batch_finish( struct vm_gk20a *vm, struct vm_gk20a_mapping_batch *batch); /* called when holding vm->update_gmmu_lock */ void gk20a_vm_mapping_batch_finish_locked( struct vm_gk20a *vm, struct vm_gk20a_mapping_batch *batch); int gk20a_vidmem_buf_alloc(struct gk20a *g, size_t bytes); int gk20a_vidmem_get_space(struct gk20a *g, u64 *space); int gk20a_vidbuf_access_memory(struct gk20a *g, struct dma_buf *dmabuf, void *buffer, u64 offset, u64 size, u32 cmd); /* Note: batch may be NULL if map op is not part of a batch */ int gk20a_vm_map_buffer(struct vm_gk20a *vm, int dmabuf_fd, u64 *offset_align, u32 flags, /* NVGPU_AS_MAP_BUFFER_FLAGS_ */ int kind, u64 buffer_offset, u64 mapping_size, struct vm_gk20a_mapping_batch *batch); int gk20a_init_vm(struct mm_gk20a *mm, struct vm_gk20a *vm, u32 big_page_size, u64 low_hole, u64 kernel_reserved, u64 aperture_size, bool big_pages, bool userspace_managed, char *name); void gk20a_deinit_vm(struct vm_gk20a *vm); /* Note: batch may be NULL if unmap op is not part of a batch */ int gk20a_vm_unmap_buffer(struct vm_gk20a *vm, u64 offset, struct vm_gk20a_mapping_batch *batch); void gk20a_get_comptags(struct device *dev, struct dma_buf *dmabuf, struct gk20a_comptags *comptags); dma_addr_t gk20a_mm_gpuva_to_iova_base(struct vm_gk20a *vm, u64 gpu_vaddr); int gk20a_dmabuf_alloc_drvdata(struct dma_buf *dmabuf, struct device *dev); int gk20a_dmabuf_get_state(struct dma_buf *dmabuf, struct device *dev, u64 offset, struct gk20a_buffer_state **state); int map_gmmu_pages(struct gk20a *g, struct gk20a_mm_entry *entry); void unmap_gmmu_pages(struct gk20a *g, struct gk20a_mm_entry *entry); void pde_range_from_vaddr_range(struct vm_gk20a *vm, u64 addr_lo, u64 addr_hi, u32 *pde_lo, u32 *pde_hi); int gk20a_mm_pde_coverage_bit_count(struct vm_gk20a *vm); u32 pte_index_from_vaddr(struct vm_gk20a *vm, u64 addr, enum gmmu_pgsz_gk20a pgsz_idx); void free_gmmu_pages(struct vm_gk20a *vm, struct gk20a_mm_entry *entry); u32 gk20a_mm_get_physical_addr_bits(struct gk20a *g); struct gpu_ops; void gk20a_init_mm(struct gpu_ops *gops); const struct gk20a_mmu_level *gk20a_mm_get_mmu_levels(struct gk20a *g, u32 big_page_size); void gk20a_mm_init_pdb(struct gk20a *g, struct mem_desc *mem, struct vm_gk20a *vm); void gk20a_remove_vm(struct vm_gk20a *vm, struct mem_desc *inst_block); int gk20a_big_pages_possible(struct vm_gk20a *vm, u64 base, u64 size); extern const struct gk20a_mmu_level gk20a_mm_levels_64k[]; extern const struct gk20a_mmu_level gk20a_mm_levels_128k[]; int gk20a_mm_get_buffer_info(struct device *dev, int dmabuf_fd, u64 *buffer_id, u64 *buffer_len); #endif /* MM_GK20A_H */