relationship between libxl & hvmloader

来源：互联网发布：河北移动crm软件编辑：程序博客网时间：2024/06/11 06:47

Hvmloader provide boot services and run-time services for hvm ，It operates on the virtual devices provided by the device models. the domain builder for HVM virtual machines uses the tools/firmware/hvmloader to create the necessary information that will enable a unmodified guest VM to work in Xen。

When we use libxl tools to create hvm domain ,it will build hvm info then step into hvmloader to load elf image.These paper introduce how the relationship between libxl &hvmloader.

xl.c

|-main.c

|-libxl_read_file_contents() // read config file from parameter

|-parse_global_config() // parse config file decide which xl command

|-cmdtable_lookup() //look cmd from config file according cmd_table

|-create_domain(&dom_info)

|-libxl_read_file_contents()

|-parse_config_data() //parse config file

|-libxl_domain_create_new() //create a new domain according config data

|-do_domain_create()

|-initiate_domain_create()

|-libxl__domain_make()

|-libxl__domain_build_info_setdefault()

|-libxl__bootloader_run() // runing bootloader

|-domcreate_bootloader_done // after bootloader_run done , do callback

|-libxl__domain_build()

|-libxl__build_pre() //

|- libxl__build_hvm() / libxl__build_pv // according dom_type {HVM, PV}

|-libxl__domain_firmware()

|-xc_hvm_build()

|-xc_read_image() //the image is hvmloader which format is elf

|-setup_guest() // copy hvmloader to special memory 【elf.pstart = 0x100000 (1M) elf.pend=

0x171764 (1M + 435388)】

|-elf_init()

|-elf_parse_binary()

|-modules_init()

|-xc_domain_set_pod_target() //Subtract 0x20 from target_pages for the VGA "hole"

|-xc_domain_populate_physmap_exact() //allocate memory for HVM guest ,skipping VGA

hole 0xA0000-0xC0000. first alloc 1G, if fails , turn 2M , also fails, turn 4k eventuraly

|-loadelfimage() // copy elf image into memory

|-elf->dest_base = xc_map_foreign_ranges(pages = pfn_end - pfn_start)

|-elf_load_binary() //load initial elf image

|-loadmodules()

|-build_hvm_info()

|-xc_set_hvm_param() // include HVM_PARAM_STORE_PFN, HVM_PARAM_BUFIOREQ_PFN,

and HVM_PARAM_IOREQ_PFN

|-xc_map_foreign_range() //running with CR0.PG=0 when using Intel EPT. Create a 32-bit

non-PAE page directory of superpages

|-elf_uval() //Insert JMP <rel32> instruction at address 0x0 to reach entry point

|-hvm_build_set_params()

|- libxl__build_post() // write into xenstore entry

|- domcreate_rebuild_done()

|-libxl_domain_unpause() // begin to run vm

|- autoconnect_vncviewer()

|- do_daemonize) // create a fork for new domain

|-libxl_create_logfile()

while(1) : while the domain start

|-domain_wait_event() //after create the domain , wait event ,according the event->type ,[SHUTDOWN

/DEATH/EJECT], do diff operation

|-console_child_report()

In all, when use libxl to create hvm domain, the hvmloader provide a virtual BIOS functiong for hvm domain.Hvmloader is loaded atxl create ，the process as follow:

[libxl]create_domain()—> parse_config_data() —>do_domain_create() —>domcreate_bootloader_done —>

libxl_domain_build_pre()—>libxl_domain_build_hvm() —>setup_guest() —>load efl image to memory

[hvmloader]—>step into hvmloader.c ,call asm —>"call main" —>hvmloader.main() —>handler_post() , load into [0xc0000 -0xfffff ] —>do_post() , call INT 0x19，boot Guest OS —>do_boot() —>boot_disk ,transfer control to Guest OS.

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