This page gives in depth descriptions:
https://cvwyg-blog.appspot.com/grub/GRUB4DOS5mlsy.htm
For Example:
MAP. Command using google translate,
map
Usage: map [--status] [--mem[=RESERV] [--top]] [--hook] [--unhook] [--unmap=DRIVES] [--rehook]
[--floppies=M] [--harddrives=N] [--memdisk-raw=RAW] [--a20-keep-on=AKO]
[--safe-mbr-hook=SMH] [--int13-scheme=SCH] [--ram-drive=RD] [--rd-base=ADDR][--rd-size=SIZE]
[[--read-only] [--fake-write] [--unsafe-boot]
[--disable-chs-mode] [--disable-lba-mode] [--heads=H] [--sectors-per-track=S] TO_DRIVE_FROM_DRIVE]
Description:
map the drive FROM_DRIVE to the drive TO_DRIVE. this is necessary when you chain-load some operating systems, such as DOS, if such an OS resides at a non-first drive. TO_DRIVE can be a disk file, this indicates a disk emulation. if --fake-write is given, any write operations to the emulated drive are allowed but the data written will be discarded. the --unsafe-boot switch enables the write to the Master and DOS boot sectors of the emulated disk. if --disable-chs=mode is given, CHS access to the emulated drive will be refused. if --disable-lba-mode is given, LBA access to the emulated drive will be refused. if RAW=1, all memdrives will be accessed without using int15/ah=87h. if RAW=0, then int15/ah=87h will be used to access memdrives. if one of --status,--hook,--unhook,--rehook,--floppies,--harddrives,--memdisk-raw, --a20-keep-on,--safe-mbr-hook,--int13-scheme,--ram-drive,--rd-base or --rd-size is given, then any other command-line arguments will be ignored. the --mem option indicates a drive in memory. if RESERV is used and <=0, the minimum memory occupied by the memdrive is (-RESERV) in 512-byte-sectors. if RESERV is used and >0 , the memdrive will occupy the mem area starting at absolute physical address RESERV in 512-byte-sectors and ending at the end of this mem block(uaually the end of physical mem).
The device mappings. This sector of the chain guide is useful features, such as DOS。
Here, the target drive(TO_DRIVE)Can be a disk file, using the virtual disk feature. Note that this requires continuous disk file is stored in the partition。
InmapCommand line，(hdm,n)+1Style of writing is interpreted as representative of the(hdm,n)Partition, rather than just the first sector of the partition.
This form
map ... (fd?)
Be a floppy emulation, and the following form
map ... (hd?)
Is a hard disk emulation.
1、Use --mem Parameter represents the mirror image of the first to be simulated is loaded into memory and then be simulated.
This parameter is required without the mirror stored in consecutive sectors. Only plus--memParameters to usefiradisk Or winvblock And other third-party drivers.
Example One： map --mem=-2880 (hd0,0)/floppy.img (fd0)
This memory drive (fd0) will occupy at least1440 KB Of memory. This usage for those less than 1440 KB of 1.44M floppy image useful.
Example 2: map --mem --read-only (hd0,0)/hd.img (hd1)
This memory drive has become a hard drive, and is read-only. This means that you can not give this (hd1) to write data.
Note: When using - mem when, even in into Windows when it seemed to be quite safe. Win98 can run memory drive.
Windows NT/2000/XP driver does not recognize the simulation, regardless of whether the - mem option.
2、0.4.5 add the parameter - top, tie - mem parameter can be loaded into high memory mirroring, such as map - mem - top (hd0, 0) / hdimg.img (hd1).
Note: The image is loaded into high memory can not use gzip compression, but not both achieve.
In grub4dos, the memory is divided into at 3.25G at high memory and low memory ends, mirroring can not cross 3.25G this point.
Such as 4G memory machines, high-end memory was about 4.0G-3.25G = 0.75G, namely 750M or so.
It should be noted that the high-end memory, and low memory can not be used simultaneously with a mirror, for example, 4G RAM, 800M volume can not be loaded into high memory mirroring，
Because the high-end memory is only 750M or so, the excess part of the low-end is not written in memory, used to pay attention.
3、Use - hook parameter represents the simulation effect immediately, even in the GRUB command line mode.
4、Parameters - unmap Usage:
map --unmap=RANGE
Which has been mapped RANGE is a BIOS drive domains. BIOS drive number 0 indicates the first floppy, 1 for the second floppy drive;
0x80 Represents the first hard drive, 0x81 for the second hard drive, and so on;
0x80 is the first hard drive, 0x81 for the second hard drive, and so on;No. actuator 0xA0 ,(hd33) Corresponds0xA1 , And so on.
Example 1:
map --unmap=0,0x80,0xff
This will reflect the shoot virtual floppy drive (fd0), virtual hard disk (hd0) and virtual CD (0xff).
Example 2:
map --unmap=0:0xff
This will reflect the radio all virtual floppy drive, all virtual hard disks and all virtual disc.
Note 1: In general, a 'map' command will drive mapping table for a virtual drive to add a table entry.
And '- unmap' means in the drive mapping table (specifically refers to a virtual drive) entries will be deleted.
Note 2: - unhook options simply disconnect INT13 hook (in the interrupt vector table). It does not affect the drive mapping table.
And in the implementation of a 'boot' command, even if it has been reflected when the shot,
INT13 disk emulator also when needed (ie, the drive mapping table is not empty) is created automatically linked.
Note 3: Normally you need to have changed the drive mapping table is performed after a `map - rehook 'command.
5、If you use the - read-only parameter, this feature allows the `disk 'is read-only;
6、If you use the - fake-write parameters, this feature allows the `disk 'in the dummy write, which can" write "data, but it is not recorded to the real disk;
7If using the - unsafe-boot parameters, this feature allows the `disk 'is true writable;
8、If you use the - disable-chs-mode parameters, CHS access functionality will be disabled;
9、If you use the - disable-lba-mode parameters, LBA access functionality will be disabled;
10、 H and S specifies the physical parameters of the virtual disk.
11、If you use the - status, - hook, - unhook, - rehook various parameters, then the other command line arguments will be ignored.
12、Parameters - safe-mbr-hook = SMH and - int13-scheme = SCH Du and Win9x environment (as stable as possible) use disk emulation related.
SMH parameter can be 0 or 1, one of the two values. As a default, SMH parameter is 1. If you encounter on Win9x disk emulation problems,
You can insert a line into the `boot 'command,
map --safe-mbr-hook=0
Then try again.
SCH when in use, it can take a value of 0 or 1. As a default, SCH is 1. If you encounter on Win9x disk emulation problems,
You can insert a line into the `boot 'command,
map --int13-scheme=0
Then try again.
By the way. Similar to the - safe-mbr-hook and - int13-scheme, MAP command, there are several other options that can be used to set the global variables.
13、 map --floppies=M
Wherein M may be 0, 1, or 2. MAP will set an appropriate value of M at the address 0040:0010.
map --harddrives=N
Where N can be from 0 to 127 values. MAP will place the value of N is set at 0040:0075.
Note: 1, BIOS data area, the total number of floppy and hard disk during the mapping has not been changed. When the board is not configured real floppy drive,
You should generally use exclusively as 'map - floppioes =' and 'map - harddrives =' to set them.
If you do not, DOS may fail to start.
2、‘map --floppies=’和‘map --harddrives= 'Needs before mapping is not performed alone.
14、 map --memdisk-raw=RAW
RAW which defaults to 1, to prevent the BIOS does not support interrupts int15/87h, or int18/87h support flawed.
If RAW = 0, will be int15/ah = 87h access memory drives, and memory drives to simulate similar to native mode.
15、 map --ram-drive=RD
The default is 0x7F which RD floppy number. If the random memory drive is a hard drive mirroring (the first sector contains the partition table)，
Then you can set the RD 0x80 and less than or equal to a value between 0xA0.
If it is a CD-ROM image, it needs to be set greater than or equal to 0xA0 and less than a value 0xFF.
map --rd-base=ADDR
map --rd-size=SIZE
Which specifies the memory image ADDR physical base address. SIZE specifies the number of bytes in the memory image size. ADDR default is 0.
SIZE The default value is 0, but the value of 0 indicates 4 GB, rather than the zero-byte disk.
Random memory drive can be in the GRUB environment by using (rd) device to access.
16、Parameters - in-situ was used for hard drive image or hard drive partition.
By - in-situ, we can put a logical partition symbolic use as a primary partition.
- In-situ of the mapping is the mapping of the entire drive. It is only a virtual partition table and DBR BPB on the hidden sectors.
Although disk emulation in win9x may encounter various problems, but in win9x in, in-situ mapping was run very well.
Note - in-situ mapping does not change the real partition table.
Example: map --in-situ (hd0,4)+1 (hd0)
17、Parameters - a20-keep-on, it is accessible memdrive sector after control of the A20 address line
map --a20-keep-on=0
It must be used in the "map - hook" before the command.
As a default, in the sector of RAM INT13 A20 will remain open after the visit.
If the "map - a20-keep-on = 0" is used, then the A20 INT13 interrupt status after the call and will be the same as before the INT13 interrupt calls.
18、Common examples:
grub> map --status
# Output current mapping status can report something valuable
grub> map /ADD.ISO (0xff)
grub> map --hook
grub> chainloader (0xff)
grub> boot
# The root directory ADD.ISO directly mapped to (0xff) No. Device (CD-ROM), and start
grub> map --mem /PE.ISO (0xff)
grub> map --hook
grub> chainloader (0xff)
grub> boot
# The root directory PE.ISO first loaded into memory, and then mapped to (0xff) No. Device (CD-ROM), and start
grub> map --mem /DGDOS.IMG (fd0)
grub> map --hook
grub> rootnoverify (fd0)
grub> chainloader ()+1
grub> boot
# Load the floppy image IMG file
or if you use g4b and wondered how partnew works translate partnew command.