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revision 1.53 by okuji, Tue Jan 15 09:37:15 2002 UTC revision 1.54 by okuji, Tue Jan 15 10:28:18 2002 UTC
# Line 99  This edition documents version @value{VE Line 99  This edition documents version @value{VE
99  * Configuration::               Writing your own configuration file  * Configuration::               Writing your own configuration file
100  * Network::                     Downloading OS images from a network  * Network::                     Downloading OS images from a network
101  * Serial terminal::             Using GRUB via a serial line  * Serial terminal::             Using GRUB via a serial line
102    * Preset Menu::                 Embedding a configuration file into GRUB
103  * Security::                    Improving the security  * Security::                    Improving the security
104  * Images::                      GRUB image files  * Images::                      GRUB image files
105  * Filesystem::                  Filesystem syntax and semantics  * Filesystem::                  Filesystem syntax and semantics
# Line 1242  example about a BOOTP configuration: Line 1243  example about a BOOTP configuration:
1243  foo:ht=1:ha=63655d0334a7:ip=145.71.35.127:\  foo:ht=1:ha=63655d0334a7:ip=145.71.35.127:\
1244          :bf=/nbgrub:\          :bf=/nbgrub:\
1245          :tc=.allhost:\          :tc=.allhost:\
1246          :T150="/tftpboot/menu.lst.foo":          :T150="(nd)/tftpboot/menu.lst.foo":
1247  @end group  @end group
1248  @end example  @end example
1249    
1250    Note that you should specify the drive name @code{(nd)} in the name of
1251    the configuration file. That is because you can change the root drive
1252    before downloading the configuration from the TFTP server, when the
1253    preset menu feature is used (@pxref{Preset Menu}).
1254    
1255  See the manual about your BOOTP/DHCP server, for more information. The  See the manual about your BOOTP/DHCP server, for more information. The
1256  exact syntax should differ from the example, more or less.  exact syntax should differ from the example, more or less.
1257    
# Line 1297  compatible with VT100 by default. This i Line 1303  compatible with VT100 by default. This i
1303  emulators nowadays, but you should pass the option @option{--dumb} to  emulators nowadays, but you should pass the option @option{--dumb} to
1304  the command, if your terminal emulator is not VT100-compatible or  the command, if your terminal emulator is not VT100-compatible or
1305  implements few VT100 escape sequences. If you specify the option, then  implements few VT100 escape sequences. If you specify the option, then
1306  GRUB doesn't provide you with the menu interface, because the menu  GRUB provides you with an alternative menu interface, because the normal
1307  requires several fancy features for your terminal. Instead, GRUB only  menu requires several fancy features for your terminal.
1308  gives you the hidden menu interface and the command-line interface  
1309  (@pxref{Interface}).  
1310    @node Preset Menu
1311    @chapter Embedding a configuration file into GRUB
1312    
1313    GRUB supports @dfn{preset menu} which is always loaded before starting.
1314    The preset menu feature is useful, for example, when your computer has
1315    no console but a serial cable. In this case, it is critical to set up
1316    the serial terminal as soon as possible, since you cannot see any
1317    message until the serial terminal begins to work. So it is nice to run
1318    the commands @command{serial} (@pxref{serial}) and @command{terminal}
1319    (@pxref{terminal}) sooner than anything else at the start-up time.
1320    
1321    It is slightly complicated how the preset menu works:
1322    
1323    @enumerate
1324    @item
1325    GRUB checks if the preset menu feature is used, and loads the preset
1326    menu, if available. This includes running commands and reading boot
1327    entries, like an ordinary configuration file.
1328    
1329    @item
1330    GRUB checks if the configuration file is available. Note that this check
1331    is performed @strong{regardless of the existence of the preset
1332    menu}. The configuration file is loaded, even after the preset menu was
1333    loaded.
1334    
1335    @item
1336    When the preset menu includes any boot entries, they are cleared when
1337    the configuration file is loaded. It doesn't matter whether the
1338    configuration file has any entries or no entry. The boot entries in the
1339    preset menu are used only when GRUB fails in loading the configuration
1340    file.
1341    @end enumerate
1342    
1343    To enable the preset menu feature, you must specify a file to the
1344    configure script with the option @option{--enable-preset-menu}. The file
1345    has the same semantics as normal configuration files
1346    (@pxref{Configuration}).
1347    
1348    Another point you should take care is that the diskless support
1349    (@pxref{Diskless}) diverts the preset menu. Diskless images embed a
1350    preset menu to execute the command @command{bootp} (@pxref{bootp})
1351    automatically, unless you specify your own preset menu to the configure
1352    script. This means that you must put commands to initialize a network in
1353    the preset menu yourself, because diskless images don't set it up
1354    implicitly, when you use the preset menu explicitly.
1355    
1356    Therefore, a typical preset menu used with diskless support would be
1357    like this:
1358    
1359    @example
1360    @group
1361    # Set up the serial terminal, first of all.
1362    serial --unit=0 --speed=19200
1363    terminal --timeout=0 serial
1364    
1365    # Initialize the network.
1366    dhcp
1367    @end group
1368    @end example
1369    
1370    
1371  @node Security  @node Security

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