北京大学操作系统实习JOS lab2实验报告

Í\ûßJOSž`,Œ!¥J00848231,[e-mail]29,2011Contents1Introduction22PhysicalPageManagement22.1Physicalpageanditsdatastructure................22.2Physicalmemorylayout.......................43VirtualMemory93.1Virtual,Linear,andPhysicalAddresses..............103.2Referencecounting..........................103.3PageTableManagement.......................134KernelAddressSpace204.1PermissionsandFaultIsolation...................204.2InitializingtheKernelAddressSpace................204.3AddressSpaceLayoutAlternatives.................311Í\ûߞ`¥J,008482311Introduction(žŒ-;Â†N-р'fµ×Ü
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„ö–HZkern/pmap.c-„à*ú,„ØÏkern/pmap.c12//Thesevariablesaresetbyi386_detect_memory()13staticphysaddr_tmaxpa;//Maximumphysicaladdress14size_tnpage;//Amountofphysicalmemory(inpages)15staticsize_tbasemem;//Amountofbasememory(inbytes)16staticsize_textmem;//Amountofextendedmemory(inbytes)1718//Thesevariablesaresetini386_vm_init()19pde_t*boot_pgdir;//Virtualaddressofboottimepagedirectory20physaddr_tboot_cr3;//Physicaladdressofboottimepagedirectory21staticchar*boot_freemem;//Pointertonextbyteoffreemem2223structPage*pages;//Virtualaddressofphysicalpagearray24staticstructPage_listpage_free_list;//FreelistofphysicalpagesÙÌêåS$*ØÏbootfreememŒbootpgdirM/SMï(…X„Ë0@_1/ô…8}eåûß¡@„…¹1ÎendåËMsÎËbootfreemem/IŽendÙ*(¥e„ã
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kern/pmap.c:i386vminit()1//////////////////////////////////////////////////////////////////////2//createinitialpagedirectory.3pgdir=boot_alloc(PGSIZE,PGSIZE);45memset(pgdir,0,PGSIZE);6boot_pgdir=pgdir;7boot_cr3=PADDR(pgdir);5Í\ûߞ`¥J,00848231v-bootalloc():vM…Xzô0@6M„0@µz6vi0@PADDR ebootcr3Æ/¨x86„ub0@lb:6Ù́èà¹PGSIZE:*iu„'4KB=4096BšI(inc/mmu.h-v-Ø ìb(„́8ÏPTSIZE:*uhù”žEi…X„'s1024*4KB=4MBÎbootalloc()—0„ub/\ø”„Ëå\„@傜ùM0„zô BzÅ{êñ²ê¨Kmemset¥×„z0@/pgdirs*Zß0@Ù*(ìb„å\-ùžEM0„iiiuuubbbÛLËöВzö(memset_š(žEiubù”„………888ZZZßßß000@@@bootcr3—0„/*iii000@@@Ù*ŒìMb:„Ï*0@ØÏ0•/Zß0@Ø/i0@ ÆTû¥eìe,*ž°„ýpbootalloc()kern/pmap.c:bootalloc()1staticvoid*2boot_alloc(uint32_tn,uint32_talign)3{4externcharend[];5void*v;67//Initializeboot_freememifthisisthefirsttime.8//’e