{"id":62028,"date":"2025-04-29T11:18:18","date_gmt":"2025-04-29T03:18:18","guid":{"rendered":"https:\/\/fwq.ai\/blog\/62028\/"},"modified":"2025-04-29T11:18:18","modified_gmt":"2025-04-29T03:18:18","slug":"risc-v-linux%e5%90%af%e5%8a%a8%e4%b9%8b%e9%a1%b5%e8%a1%a8%e5%88%9b%e5%bb%ba%e5%88%86%e6%9e%90-2","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/62028\/","title":{"rendered":"RISC-V Linux\u542f\u52a8\u4e4b\u9875\u8868\u521b\u5efa\u5206\u6790"},"content":{"rendered":"

\u4e0a\u7bc7\u5206\u6790\u4e86RISC-V Linux\u7684\u6c47\u7f16\u542f\u52a8\u8fc7\u7a0b\uff0c\u5176\u4e2d\u8bb2\u5230\u4e86relocate\u91cd\u5b9a\u5411\u9700\u8981\u5f00\u542fMMU\uff0c\u4eca\u5929\u5206\u6790RISC-V Linux\u7684\u9875\u8868\u521b\u5efa\u3002<\/p>\n

\n

\u6ce8\u610f\uff1a\u672c\u6587\u57fa\u4e8e5.10.111\u5185\u6838<\/p>\n<\/blockquote>\n

<\/span>sv39 mmu<\/span> <\/span> <\/h2>\n

RISC-V Linux\u652f\u6301sv32\u3001sv39\u3001sv48\u7b49\u865a\u62df\u5730\u5740\u683c\u5f0f\uff0c\u5206\u522b\u4ee3\u886832\u4e3a\u865a\u62df\u5730\u5740\u300138\u4f4d\u865a\u62df\u5730\u5740\u548c48\u4f4d\u865a\u62df\u5730\u5740\u3002RISC-V Linux\u9ed8\u8ba4\u4e5f\u662f\u4f7f\u7528sv39\u683c\u5f0f\uff0csv39\u7684\u865a\u62df\u5730\u5740\u3001\u7269\u7406\u5730\u5740\u3001PTE\u683c\u5f0f\u5982\u4e0b\uff1a<\/p>\n

\u865a\u62df\u5730\u5740\u683c\u5f0f\uff1a<\/p>\n

\"RISC-V <\/p>\n

\u7269\u7406\u5730\u5740\u683c\u5f0f\uff1a<\/p>\n

\"RISC-V <\/p>\n

PTE\u683c\u5f0f\uff1a<\/p>\n

\"RISC-V <\/p>\n

\u865a\u62df\u5730\u5740\u4f7f\u752839\u4f4d\u8868\u793a\uff0c\u5176\u4e2d\u4f4e12\u4f4d\u4ee3\u8868page offset\uff0c\u9ad8\u4f4d\u5212\u5206\u4e3a\u4e86\u4e09\u90e8\u5206\uff1aVP N[0]\u3001VP N[1]\u548cVP N[2]\uff0c\u5206\u522b\u4ee3\u8868\u865a\u62df\u5730\u5740VA\u5728PTE\u3001PMD\u548cPGD\u4e2d\u7684\u7d22\u5f15\u3002<\/p>\n

\u7269\u7406\u5730\u5740\u4f7f\u752856\u4f4d\u8868\u793a\uff0c\u4f4e12\u4f4d\u4ee3\u8868page offset\uff0c\u9ad8\u4f4d\u662f\u7269\u7406\u9875PPN[0]\u3001PPN[1]\u548cPPN[2]<\/p>\n

PTE\u4fdd\u5b58\u4e86\u7269\u7406\u9875PPN[0]\u3001PPN[1]\u548cPPN[2]\uff0c\u548c\u7269\u7406\u5730\u5740\u4e2d\u7684PPN\u76f8\u5bf9\u5e94\uff1bPTE\u7684\u4f4e10\u4f4d\u4ee3\u8868\u7269\u7406\u5730\u5740\u7684\u8bbf\u95ee\u6743\u9650\uff0c\u5f53RWX\u5168\u4e3a0\u65f6\uff0c\u5219\u4ee3\u8868\u8be5PTE\u5b58\u50a8\u7684\u5730\u5740\u662f\u4e0b\u4e00\u7ea7\u9875\u8868\u7684\u7269\u7406\u5730\u5740\uff0c\u5426\u5219\u4ee3\u8868\u5f53\u524d\u9875\u8868\u662f\u6700\u540e\u4e00\u7ea7\u9875\u8868<\/strong>\u3002<\/p>\n

\u518d\u770b\u770bsv39 \u7684\u9875\u8868\u683c\u5f0f\uff0csv39\u4f7f\u7528\u7684\u662f\u4e09\u7ea7\u9875\u8868\uff0cPGD\u3001PMD\u548cPTE\uff0c\u6bcf\u4e00\u4e2a\u7ea7\u9875\u8868\u4f7f\u75289bit\u8868\u793a\uff0c\u5373\u6bcf\u4e00\u7ea7\u9875\u8868\u90fd\u6709512\u4e2a\u9875\u8868\u9879\u3002<\/p>\n

\u5728\u4ee3\u7801\u4e2d\uff0c\u521b\u5efa\u4e00\u4e2a\u6709512\u4e2a\u5143\u7d20\u7684\u6570\u7ec4\u5373\u4ee3\u8868\u4e00\u4e2a\u9875\u8868\u3002\u4e00\u4e2aPTE\u6709512\u4e2a\u9875\u8868\u9879\uff0c\u6bcf\u4e00\u4e2a\u9875\u8868\u9879\u5360\u75288\u5b57\u8282\uff0c512*8=4096\u5b57\u8282\uff0c\u6240\u4ee5\u4e00\u4e2aPTE\u4ee3\u88684K\u3002\u4e00\u4e2aPMD\u4e5f\u662f512\u4e2a\u9875\u8868\u9879\uff0c\u6bcf\u4e00\u9879\u53ef\u4ee3\u8868\u4e00\u4e2aPTE\uff0c512 *4 K=2M\uff0c\u6240\u4ee5\u4e00\u4e2aPMD\u5c31\u4ee3\u88682M\u3002\u4ee5\u6b64\u7c7b\u63a8\uff0c\u4e00\u4e2aPGD\u4ee3\u8868512 * 2M=1G\u3002<\/p>\n

\u91cd\u8981\u7ed3\u8bba\uff1aPGD\u4ee3\u88681G\u3001PMD\u4ee3\u88682M\u3001PTE\u4ee3\u88684K\u3002sv39\u9ed8\u8ba4\u7684\u9875\u5927\u5c0f\u662f4K<\/strong>\u3002<\/p>\n

\u4e09\u7ea7\u9875\u8868\u865a\u62df\u5730\u5740\u8f6c\u4e3a\u7269\u7406\u5730\u5740\u8fc7\u7a0b\u793a\u610f\u56fe\uff1a\"RISC-V<\/p>\n

sv39\u4e09\u7ea7\u9875\u8868\u865a\u62df\u5730\u5740\u8f6c\u4e3a\u7269\u7406\u5730\u5740\u8fc7\u7a0b\uff1a<\/p>\n

MMU\u901a\u8fc7satp\u5bc4\u5b58\u5668\u5f97\u5230PGD\u7684\u7269\u7406\u5730\u5740\uff0c\u7ed3\u5408PGD index\uff08\u5373V PN[2]\uff09\u627e\u5230PMD\uff1b\u627e\u5230PMD\u540e\uff0c\u518d\u7ed3\u5408PMD index\uff08\u5373V PN[1]\uff09\u627e\u5230PTE\uff0c\u7136\u540e\u7ed3\u5408PTE index\uff08\u5373V PN[0]\uff09\u5f97\u5230VA\u5728PTE\u7d22\u5f15\u4e2d\u7684\u503c\uff0c\u4ece\u800c\u5f97\u5230\u7269\u7406\u5730\u5740\u3002<\/p>\n

\u6700\u540e\u5728PTE\u4e2d\u53d6\u51faPPN[2]\u3001PPN[1]\u548cPPN[0],\u518d\u548c\u865a\u62df\u5730\u5740\u7684\u4f4e12\u4f4doffset\u76f8\u52a0\uff0c\u5f97\u5230\u6700\u7ec8\u7684\u7269\u7406\u5730\u5740\u3002<\/p>\n

<\/span>\u4e34\u65f6\u9875\u8868\u5206\u6790<\/span> <\/span> <\/h2>\n

MMU\u5f00\u542f\u524d\uff0c\u9700\u8981\u5efa\u7acb\u597dkernel\u3001dtb\u3001trampoline\u7b49\u9875\u8868\u3002\u4ee5\u4fbfMMU\u5f00\u542f\u540e\uff0c\u5e76\u4e14\u5728\u5185\u5b58\u7ba1\u7406\u6a21\u5757\u8fd0\u884c\u4e4b\u524d\uff0ckernel\u53ef\u4ee5\u6b63\u5e38\u521d\u59cb\u5316\uff0cdtb\u53ef\u4ee5\u6b63\u5e38\u5730\u88ab\u89e3\u6790\u3002\u8fd9\u90e8\u5206\u9875\u8868\u90fd\u662f\u4e34\u65f6\u9875\u8868\uff0c\u6700\u7ec8\u7684\u9875\u8868\u5728setup_vm_final()\u5efa\u7acb\u3002<\/p>\n

\u4e34\u65f6\u9875\u8868\u521b\u5efa\u987a\u5e8f\uff1a<\/p>\n

\u9996\u5148\u4e3afixmap\u521b\u5efa\u65e9\u671f\u7684PGD\u3001PMD\uff0c\u8fd9\u65f6PGD\u4f7f\u7528early_pg_dir\u3002\u7136\u540e\u5bf9\u4ecekernel\u5f00\u59cb\u7684\u524d2M\u5185\u5b58\u5efa\u7acb\u4e8c\u7ea7\u9875\u8868\uff0c\u6b64\u65f6PGD\u4f7f\u7528trampoline_pg_dir\uff0c\u4e3a\u8fd92M\u5efa\u7acb\u7684\u9875\u8868\u4e5f\u53eb\u4f5csuperpage\u3002\u518d\u7136\u540e\uff0c\u5bf9\u6574\u4e2akernel\u521b\u5efa\u4e8c\u7ea7\u9875\u8868\uff0c\u6b64\u65f6PGD\u4f7f\u7528early_pg_dir\u3002\u6700\u540e\u4e3adtb\u9884\u75594M\u5927\u5c0f\u521b\u5efa\u4e8c\u7ea7\u9875\u8868\u3002<\/p>\n

<\/span>\u9875\u8868\u521b\u5efa\u51fd\u6570<\/span> <\/span> <\/h2>\n

<\/span>create_pgd_mapping()<\/span> <\/h3>\n
void __init create_pgd_mapping(pgd_t *pgdp,\n          uintptr_t va, phys_addr_t pa,\n          phys_addr_t sz, pgprot_t prot)<\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
pgdp\uff1aPGD\u9875\u8868<\/p>\n
va\uff1a\u865a\u62df\u5730\u5740<\/p>\n
pa\uff1a\u7269\u7406\u5730\u5740<\/p>\n
sz\uff1a\u6620\u5c04\u5927\u5c0f\uff0cPGDIR_SIZE\u6216PMD_SIZE\u6216PTE_SIZE<\/p>\n
prot\uff1aPAGE_KERNEL_EXEC\/PAGE_KERNEL\u8868\u793a\u5f53\u524d\u662f\u6700\u540e\u4e00\u7ea7\u9875\u8868\uff0c\u5426\u5219pa\u4ee3\u8868\u4e0b\u4e00\u7ea7\u9875\u8868\u7684\u7269\u7406\u5730\u5740<\/p>\n
 <\/span>create_pmd_mapping()<\/span> <\/h3>\n
static void __init create_pmd_mapping(pmd_t *pmdp,\n          uintptr_t va, phys_addr_t pa,\n          phys_addr_t sz, pgprot_t prot)<\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
pmdp\uff1aPMD\u9875\u8868<\/p>\n
va\uff1a\u865a\u62df\u5730\u5740<\/p>\n
pa\uff1a\u7269\u7406\u5730\u5740<\/p>\n
sz\uff1a\u6620\u5c04\u5927\u5c0f\uff0cPMD_SIZE\u6216PAGE_SIZE<\/p>\n
prot\uff1a\u6743\u9650\uff0cPAGE_KERNEL_EXEC\/PAGE_KERNEL\u8868\u793a\u5f53\u524d\u662f\u6700\u540e\u4e00\u7ea7\u9875\u8868\uff0c\u5426\u5219pa\u4ee3\u8868\u4e0b\u4e00\u7ea7\u9875\u8868\u7684\u7269\u7406\u5730\u5740<\/p>\n
 <\/span>create_pte_mapping()<\/span> <\/h3>\n
static void __init create_pte_mapping(pte_t *ptep,\n          uintptr_t va, phys_addr_t pa,\n          phys_addr_t sz, pgprot_t prot)<\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
ptep\uff1aPTE\u9875\u8868<\/p>\n
va\uff1a\u865a\u62df\u5730\u5740<\/p>\n
pa\uff1a\u7269\u7406\u5730\u5740<\/p>\n
sz\uff1a\u6620\u5c04\u5927\u5c0f\uff0cPAGE_SIZE<\/p>\n
prot\uff1a\u6743\u9650\uff0cPAGE_KERNEL_EXEC\/PAGE_KERNEL\u8868\u793a\u5f53\u524d\u662f\u6700\u540e\u4e00\u7ea7\u9875\u8868\uff0c\u5426\u5219pa\u4ee3\u8868\u4e0b\u4e00\u7ea7\u9875\u8868\u7684\u7269\u7406\u5730\u5740<\/p>\n
 <\/span>\u4f7f\u7528\u4e3e\u4f8b<\/span> <\/h3>\n
\u4f8b\u5982\uff0c\u5c06\u865a\u62df\u5730\u5740PAGE_OFFSET\u6620\u5c04\u5230\u7269\u7406\u5730\u5740pa\uff0c\u6620\u5c04\u5927\u5c0f\u4e3a4K\uff0c\u521b\u5efa\u4e09\u7ea7\u9875\u8868PGD\u3001PMD\u548cPTE\uff1a<\/p>\n
create_pgd_mapping(early_pg_dir\uff0cPAGE_OFFSET\uff0c\n                   (uintptr_t)early_pmd\uff0cPGDIR_SIZE,PAGE_TABLE);\ncreate_pmd_mapping(early_pmd\uff0cPAGE_OFFSET\uff0c\n                   (uintptr_t)early_pte\uff0cPGDIR_SIZE,PAGE_TABLE);\ncreate_pte_mapping(early_pte\uff0cPAGE_OFFSET\uff0c\n                   (uintptr_t)pa\uff0cPAGE_SIZE,PAGE_KERNEL_EXEC);<\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
\u8fd9\u6837\u521b\u5efa\u540e\uff0cMMU\u5c31\u4f1a\u6839\u636ePAGE_OFFSET\u5728PGD\u4e2d\u627e\u5230PMD\uff0c\u7136\u540e\u518dPMD\u4e2d\u627e\u5230PTE\uff0c\u6700\u540e\u53d6\u51fa\u7269\u7406\u5730\u5740\u3002<\/p>\n
 <\/span>\u9875\u8868\u521b\u5efa\u6e90\u7801\u5206\u6790<\/span> <\/span> <\/h2>\n
RISC-V Linux\u542f\u52a8\uff0c\u7ecf\u5386\u4e86\u4e24\u6b21\u9875\u8868\u521b\u5efa\u8fc7\u7a0b\uff0c\u7b2c\u4e00\u6b21\u4f7f\u7528C\u51fd\u6570setup_vm()\u521b\u5efa\u4e34\u65f6\u9875\u8868\uff0c\u7b2c\u4e8c\u6b21\u4f7f\u7528C\u51fd\u6570setup_vm_final()\u521b\u5efa\u6700\u7ec8\u9875\u8868\u3002<\/p>\n
\u5177\u4f53\u7ec6\u8282\u53c2\u8003\u4ee3\u7801\u4e2d\u7684\u6ce8\u91ca\uff0c\u4e0b\u9762\u7684\u4ee3\u7801\u7701\u7565\u4e86\u4e00\u4e9b\u4e0d\u91cd\u8981\u7684\u90e8\u5206\u3002<\/p>\n
 <\/span>setup_vm()<\/span> <\/h3>\n
asmlinkage void __init setup_vm(uintptr_t dtb_pa)\n{\n uintptr_t va, pa, end_va;\n uintptr_t load_pa = (uintptr_t)(&amp;_start);\n uintptr_t load_sz = (uintptr_t)(&amp;_end) - load_pa;\n uintptr_t map_size;\n \/\/load_pa\u5c31\u662fkernel\u52a0\u8f7d\u7684\u5176\u5b9e\u7269\u7406\u5730\u5740\n    \/\/load_sz\u5c31\u662fkernel\u7684\u5b9e\u9645\u5927\u5c0f\n\n    \/\/page_offset\u5c31\u662fkernel\u7684\u8d77\u59cb\u7269\u7406\u5730\u5740\u5bf9\u5e94\u7684\u865a\u62df\u5730\u5740\uff0cva_pa_offset\u662f\u4ed6\u4eec\u7684\u504f\u79fb\u91cf\n va_pa_offset = PAGE_OFFSET - load_pa;\n    \n    \/\/\u8ba1\u7b97\u5f97\u5230kernel\u8d77\u59cb\u7269\u7406\u5730\u5740\u7684\u7269\u7406\u9875\uff0cPFN_DOWN\u662f\u5c06\u7269\u7406\u5730\u5740\u53f3\u79fb12\u4f4d\uff0c\u56e0\u4e3asv39\u7684\u7269\u7406\u5730\u5740\u7684\u4f4e12\u4f4d\u662fpa_offset\uff0c\u6240\u4ee5\u53f3\u79fb12\u4f4d\uff0c\u5f97\u5230pfn\n pfn_base = PFN_DOWN(load_pa);\n\n map_size = PMD_SIZE;\/\/PMD_SIZE\u4e3a2M\uff0c\u5728\u5f53\u524d\uff0cmap_size\u53ea\u80fd\u4e3aPGDIR_SIZE\u6216PMD_SIZE\u3002\u8fd9\u65f6kernel\u9ed8\u8ba4\u4e0d\u5141\u8bb8\u5efa\u7acbPTE\u3002\n\n \/\/\u68c0\u67e5PAGE_OFFSET\u662f\u54261G\u5bf9\u9f50\uff0c\u4ee5\u53cakernel\u5165\u53e3\u5730\u5740\u662f\u54262M\u5bf9\u9f50\n BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);\n BUG_ON((load_pa % map_size) != 0);\n\n    \/\/allc_pte_early\u91cc\u9762\u662fBUG(),\u5bf9\u4e8e\u4e34\u65f6\u9875\u8868\uff0ckernel\u4e0d\u5141\u8bb8\u6211\u4eec\u5efa\u7acbPTE\n pt_ops.alloc_pte = alloc_pte_early;\n pt_ops.get_pte_virt = get_pte_virt_early;\n#ifndef __PAGETABLE_PMD_FOLDED\n pt_ops.alloc_pmd = alloc_pmd_early;\n pt_ops.get_pmd_virt = get_pmd_virt_early;\n#endif\n \/* \u8bbe\u7f6e early PGD for fixmap *\/\n create_pgd_mapping(early_pg_dir, FIXADDR_START,\n      (uintptr_t)fixmap_pgd_next, PGDIR_SIZE, PAGE_TABLE);\n\n\n \/* \u8bbe\u7f6e fixmap PMD *\/\n create_pmd_mapping(fixmap_pmd, FIXADDR_START,\n      (uintptr_t)fixmap_pte, PMD_SIZE, PAGE_TABLE);\n \/* \u8bbe\u7f6e trampoline PGD and PMD *\/\n create_pgd_mapping(trampoline_pg_dir, PAGE_OFFSET,\n      (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE);\n create_pmd_mapping(trampoline_pmd, PAGE_OFFSET,\n      load_pa, PMD_SIZE, PAGE_KERNEL_EXEC);\n\n \/*\n  * \u8bbe\u7f6e\u8986\u76d6\u6574\u4e2a\u5185\u6838\u7684\u65e9\u671fPGD\uff0c\u8fd9\u5c06\u4f7f\u6211\u4eec\u80fd\u591f\u8fbe\u5230paging_init\uff08\uff09\u3002\n  * \u7a0d\u540e\u5728\u4e0b\u9762\u7684 setup_vm_final\uff08\uff09 \u4e2d\u6620\u5c04\u6240\u6709\u5185\u5b58\u3002\n  *\/\n end_va = PAGE_OFFSET + load_sz;\n for (va = PAGE_OFFSET; va <blockquote data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"border-top: none;border-right: none;border-bottom: none;font-size: 0.9em;overflow: auto;color: rgb(106, 115, 125);padding: 10px 10px 10px 20px;margin-bottom: 20px;margin-top: 20px;border-left-color: rgb(239, 112, 96);background: rgb(255, 249, 249);\">\n<p style=\"font-size: 16px;padding-top: 8px;padding-bottom: 8px;color: black;line-height: 26px;\">setup_vm()\u5728\u6700\u5f00\u59cb\u5c31\u8fdb\u884c\u4e86kernel\u5165\u53e3\u5730\u5740\u7684\u5bf9\u9f50\u68c0\u67e5\uff0c\u8981\u6c42\u5165\u53e3\u5730\u57402M\u5bf9\u9f50\u3002\u5047\u8bbe\u5185\u5b58\u8d77\u59cb\u5730\u5740\u4e3a0x80000000\uff0c\u90a3\u4e48kernel\u53ea\u80fd\u653e\u57280x80000000\u30010x80200000\u7b492M\u5bf9\u9f50\u5904\u3002\u4e3a\u4ec0\u4e48\u4f1a\u6709\u8fd9\u79cd\u5bf9\u9f50\u8981\u6c42\u5462\uff1f<\/p>\n<p style=\"font-size: 16px;padding-top: 8px;padding-bottom: 8px;color: black;line-height: 26px;\">\u6211\u731c\u6d4b\u5355\u7eaf\u662f\u4e3a\u7ed9opensbi\u9884\u7559\u4e862M\u7a7a\u95f4\uff0c\u56e0\u4e3akernel\u4e4b\u524d\u8fd8\u6709opensbi\uff0c\u800copensbi\u8fd0\u884c\u5b8c\u4e4b\u540e\uff0c\u9ed8\u8ba4\u8df3\u8f6c\u5730\u5740\u5c31\u662f\u504f\u79fb2M\uff0ckernel\u53ea\u662f\u4e3a\u4e86\u8ddfopensbi\u5bf9\u5e94\uff0c\u6240\u4ee5\u8bbe\u7f6e\u4e862M\u5bf9\u9f50\u3002<\/p>\n<p style=\"font-size: 16px;padding-top: 8px;padding-bottom: 8px;color: black;line-height: 26px;\">\u90a3opensbi\u9700\u8981\u5360\u75282M\u8fd9\u4e48\u5927\uff1f\u5b9e\u9645\u4e0a\u53ea\u9700\u8981\u51e0\u767eKB\uff0c\u56e0\u6b64opensbi\u548ckernel\u4e2d\u95f4\u6709\u4e00\u6bb5\u5185\u5b58\u662f\u7a7a\u95f2\u7684\uff0c\u6ca1\u6709\u4eba\u4f7f\u7528\u3002\u8fd9\u4e2a\u95ee\u9898\u6211\u4eec\u4e0b\u7bc7\u518d\u8bb2\u3002<\/p>\n<\/blockquote><h3 data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"margin-top: 30px;margin-bottom: 15px;font-weight: bold;font-size: 20px;\">\n<span style=\"display: none;\"><\/span>setup_vm_final()<span style=\"display: none;\"><\/span>\n<\/h3><p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">\u5728\u8be5\u51fd\u6570\u4e2d\u5f00\u59cb\u4e3a\u6574\u4e2a\u7269\u7406\u5185\u5b58\u505a\u5185\u5b58\u6620\u5c04\uff0c\u901a\u8fc7swapper\u9875\u8868\u6765\u7ba1\u7406\uff0c\u5e76\u4e14\u6e05\u9664\u6389\u6c47\u7f16\u9636\u6bb5\u7684\u9875\u8868\u3002<\/p><pre class=\"brush:php;toolbar:false;\">static void __init setup_vm_final(void)\n{\n uintptr_t va, map_size;\n phys_addr_t pa, start, end;\n u64 i;\n\n \/**\n  * \u6b64\u65f6MMU\u5df2\u7ecf\u5f00\u542f\uff0c\u4f46\u662f\u9875\u8868\u8fd8\u6ca1\u5b8c\u5168\u5efa\u7acb\u3002\n  *\/\n pt_ops.alloc_pte = alloc_pte_fixmap;\n pt_ops.get_pte_virt = get_pte_virt_fixmap;\n#ifndef __PAGETABLE_PMD_FOLDED\n pt_ops.alloc_pmd = alloc_pmd_fixmap;\n pt_ops.get_pmd_virt = get_pmd_virt_fixmap;\n#endif\n \/* Setup swapper PGD for fixmap *\/\n create_pgd_mapping(swapper_pg_dir, FIXADDR_START,\n      __pa_symbol(fixmap_pgd_next),\n      PGDIR_SIZE, PAGE_TABLE);\n\n \/* \u4e3a\u6574\u4e2a\u7269\u7406\u5185\u5b58\u521b\u5efa\u9875\u8868 *\/\n for_each_mem_range(i, &amp;start, &amp;end) {\n  if (start &gt;= end)\n   break;\n  if (start <p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">\u8bf4\u660e\uff1a<\/p><p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">\u5728setup_vm_final()\u51fd\u6570\u4e2d\uff0c\u901a\u8fc7swapper_pg_dir\u9875\u8868\u6765\u7ba1\u7406\u6574\u4e2a\u7269\u7406\u5185\u5b58\u7684\u8bbf\u95ee\u3002\u5e76\u4e14\u6e05\u9664\u6c47\u7f16\u9636\u6bb5\u7684\u9875\u8868fixmap_pte\u548cearly_pg_dir\u3002\uff08\u672c\u8d28\u4e0a\u5c31\u662f\u628a\u8be5\u9875\u8868\u9879\u7684\u5185\u5bb9\u6e050\uff0c\u5373\u8d4b\u503c\u4e3a0\uff09<\/p><p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">\u6700\u7ec8\u628aswapper_pg_dir\u9875\u8868\u7684\u7269\u7406\u5730\u5740\u8d4b\u503c\u7ed9SATP\u5bc4\u5b58\u5668\u3002\u8fd9\u6837CPU\u5c31\u53ef\u4ee5\u901a\u8fc7\u8be5\u9875\u8868\u8bbf\u95ee\u6574\u4e2a\u7269\u7406\u5185\u5b58\u3002<\/p><p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">\u5207\u6362\u9875\u8868\u901a\u8fc7\u5982\u4e0b\u5b9e\u73b0\uff1a<\/p><p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">csr_write(CSR_SATP,PFN_DOWN(_pa(swapper_pg_dir))|SATP_MODE);<\/p><p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">\u5728swapper_pg_dir\u7ba1\u7406\u7684kernel space\u4e2d\uff0c\u5176\u865a\u62df\u5730\u5740\u4e0e\u7269\u7406\u5730\u5740\u7a7a\u95f4\u7684\u504f\u79fb\u662f\u56fa\u5b9a\u7684\uff0c\u4e3ava_pa_offset\uff08\u5b9a\u4e49\u5728arch\/riscv\/mm\/init.c\u4e2d\u7684\u4e00\u4e2a\u5168\u5c40\u53d8\u91cf\uff09<\/p><blockquote data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"border-top: none;border-right: none;border-bottom: none;font-size: 0.9em;overflow: auto;color: rgb(106, 115, 125);padding: 10px 10px 10px 20px;margin-bottom: 20px;margin-top: 20px;border-left-color: rgb(239, 112, 96);background: rgb(255, 249, 249);\"><p style=\"font-size: 16px;padding-top: 8px;padding-bottom: 8px;color: black;line-height: 26px;\">\u6ce8\u610f\uff1aswapper_pg_dir\u7ba1\u7406\u7684\u662fkernel space\u7684\u9875\u8868\uff0c\u5373\u5b83\u628a\u7269\u7406\u5185\u5b58\u6620\u5c04\u5230\u7684\u865a\u62df\u5730\u5740\u7a7a\u95f4\u662f\u53ea\u80fdkernel\u8bbf\u95ee\u7684\u3002user space\u4e0d\u80fd\u8bbf\u95ee\uff0c\u7528\u6237\u7a7a\u95f4\u5982\u679c\u8bbf\u95ee\uff0c\u5fc5\u987b\u81ea\u884c\u5efa\u7acb\u9875\u8868\uff0c\u628a\u7269\u7406\u5730\u5740\u6620\u5c04\u5230user space\u7684\u865a\u62df\u5730\u5740\u7a7a\u95f4\u3002kernel\u7ebf\u7a0b\u5171\u4eab\u8fd9\u4e2aswapper_pg_dir\u9875\u8868\u3002<\/p><\/blockquote><h2 data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"margin-top: 30px;margin-bottom: 15px;font-weight: bold;border-bottom: 1px solid rgb(239, 112, 96);font-size: 1.3em;\">\n<span style=\"display: none;\"><\/span><span style=\"display: inline-block;background: rgb(239, 112, 96);color: rgb(255, 255, 255);padding: 2px 10px 1px;border-top-right-radius: 3px;border-top-left-radius: 3px;margin-right: 3px;\">\u603b\u7ed3<\/span><span style=\"display: inline-block;vertical-align: bottom;border-bottom: 36px solid #efebe9;border-right: 20px solid transparent;\"> <\/span>\n<\/h2><p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">RISC-V Linux\u542f\u52a8\u65f6\u7684\u9875\u8868\u521b\u5efa\u76f8\u5bf9\u6765\u8bf4\u8fd8\u662f\u6bd4\u8f83\u5bb9\u6613\u7406\u89e3\u7684\uff0c\u90fd\u662fC\u8bed\u8a00\u521b\u5efa\u7684\uff0c\u4ee3\u7801\u4e5f\u6bd4\u8f83\u5c11\u3002\u4e3b\u8981\u5c31\u662fsetup_vm()\u548csetup_vm_final()\u4e24\u4e2a\u9875\u8868\u521b\u5efa\u51fd\u6570\u3002\u7406\u89e3\u4e86sv39\u7684\u4e00\u4e9b\u5730\u5740\u683c\u5f0f\u540e\uff0c\u518d\u53bb\u5206\u6790\u6e90\u7801\u5c31\u6bd4\u8f83\u5bb9\u6613\u3002\u4e0d\u8fc7\u4e0d\u540ckernel\u7248\u672c\u4ee3\u7801\u90fd\u4e0d\u4e00\u6837\uff0c\u9700\u8981\u5177\u4f53\u60c5\u51b5\u5177\u4f53\u5206\u6790\u3002<\/p><p data-tool=\"mdnice\u7f16\u8f91\u5668\" style=\"padding-top: 8px;padding-bottom: 8px;line-height: 26px;\">\u672c\u7bc7\u63d0\u5230\u4e86setup_vm()\u4f1a\u68c0\u67e5kernel\u5165\u53e3\u5730\u5740\u662f\u54262M\u5bf9\u9f50\uff0c\u5982\u679c\u4e0d\u5bf9\u9f50kernel\u65e0\u6cd5\u542f\u52a8\uff0c\u4f46\u5176\u5b9e\u6211\u4eec\u53ef\u4ee5\u89e3\u9664\u8fd9\u4e2a2M\u5bf9\u9f50\u9650\u5236\uff0c\u5c06\u8fd9\u90e8\u5206\u7a7a\u95f4\u5229\u7528\u8d77\u6765\uff0c\u4e0b\u7bc7\u6559\u5927\u5bb6\u4f18\u5316\u8fd9\u90e8\u5206\u5185\u5b58\u3002<\/p><\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
\u4ee5\u4e0a\u5c31\u662fRISC-V Linux\u542f\u52a8\u4e4b\u9875\u8868\u521b\u5efa\u5206\u6790\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8FDCServers\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e0a\u7bc7\u5206\u6790\u4e86RISC-V Linux\u7684\u6c47\u7f16\u542f\u52a8\u8fc7\u7a0b\uff0c\u5176\u4e2d\u8bb2\u5230\u4e86relocate\u91cd\u5b9a\u5411\u9700\u8981\u5f00\u542fMMU\uff0c\u4eca\u5929\u5206\u6790RISC-V Linux\u7684\u9875\u8868\u521b\u5efa\u3002 \u6ce8\u610f\uff1a\u672c\u6587\u57fa\u4e8e5.10.111\u5185\u6838 sv39 mmu RISC-V Linux\u652f\u6301sv32\u3001sv39\u3001sv48\u7b49\u865a\u62df\u5730\u5740\u683c\u5f0f\uff0c\u5206\u522b\u4ee3\u886832\u4e3a\u865a\u62df\u5730\u5740\u300138\u4f4d\u865a\u62df\u5730\u5740\u548c48\u4f4d\u865a\u62df\u5730\u5740\u3002RISC-V Linux\u9ed8\u8ba4\u4e5f\u662f\u4f7f\u7528sv39\u683c\u5f0f\uff0csv39\u7684\u865a\u62df\u5730\u5740\u3001\u7269\u7406\u5730\u5740\u3001PTE\u683c\u5f0f\u5982\u4e0b\uff1a \u865a\u62df\u5730\u5740\u683c\u5f0f\uff1a \u7269\u7406\u5730\u5740\u683c\u5f0f\uff1a PTE\u683c\u5f0f\uff1a \u865a\u62df\u5730\u5740\u4f7f\u752839\u4f4d\u8868\u793a\uff0c\u5176\u4e2d\u4f4e12\u4f4d\u4ee3\u8868page offset\uff0c\u9ad8\u4f4d\u5212\u5206\u4e3a\u4e86\u4e09\u90e8\u5206\uff1aVP N[0]\u3001VP N[1]\u548cVP N[2]\uff0c\u5206\u522b\u4ee3\u8868\u865a\u62df\u5730\u5740VA\u5728PTE\u3001PMD\u548cPGD\u4e2d\u7684\u7d22\u5f15\u3002 \u7269\u7406\u5730\u5740\u4f7f\u752856\u4f4d\u8868\u793a\uff0c\u4f4e12\u4f4d\u4ee3\u8868page offset\uff0c\u9ad8\u4f4d\u662f\u7269\u7406\u9875PPN[0]\u3001PPN[1]\u548cPPN[2] PTE\u4fdd\u5b58\u4e86\u7269\u7406\u9875PPN[0]\u3001PPN[1]\u548cPPN[2]\uff0c\u548c\u7269\u7406\u5730\u5740\u4e2d\u7684PPN\u76f8\u5bf9\u5e94\uff1bPTE\u7684\u4f4e10\u4f4d\u4ee3\u8868\u7269\u7406\u5730\u5740\u7684\u8bbf\u95ee\u6743\u9650\uff0c\u5f53RWX\u5168\u4e3a0\u65f6\uff0c\u5219\u4ee3\u8868\u8be5PTE\u5b58\u50a8\u7684\u5730\u5740\u662f\u4e0b\u4e00\u7ea7\u9875\u8868\u7684\u7269\u7406\u5730\u5740\uff0c\u5426\u5219\u4ee3\u8868\u5f53\u524d\u9875\u8868\u662f\u6700\u540e\u4e00\u7ea7\u9875\u8868\u3002 \u518d\u770b\u770bsv39 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prot\uff1aPAGE_KERNEL_EXEC\/PAGE_KERNEL\u8868\u793a\u5f53\u524d\u662f\u6700\u540e\u4e00\u7ea7\u9875\u8868\uff0c\u5426\u5219pa\u4ee3\u8868\u4e0b\u4e00\u7ea7\u9875\u8868\u7684\u7269\u7406\u5730\u5740 create_pmd_mapping() static void __init create_pmd_mapping(pmd_t *pmdp, 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