On 1 Jan 90 at 5:00, pavelat_private wrote: [snip] > Magic SysRq is in "kernel hacking" section. If you enable it, and you > are not kernel hacker, you loose. (If you are kernel hacker, you > certainly don't want mere mortals access your console, do you? > > Read help entry: > > CONFIG_MAGIC_SYSRQ > If you say Y here, you will have some control over the system even > if the system crashes for example during kernel debugging (e.g., you > will be able to flush the buffer cache to disk, reboot the system > immediately or dump some status information). This is accomplished > by pressing various keys while holding SysRq (Alt+PrintScreen). The > keys are documented in Documentation/sysrq.txt. Don't say Y unless > !!!!!!!!!!!!!!!!!! > you really know what this hack does. > !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! > > If you did not realize it allows people to bypass vlock -a, you did > not know what it does, and you should not have enabled it :-). CONFIG_MAGIC_SYSRQ is enabled by default in the 2.2.5 kernel which is shipped with RedHat-6.0: viper:/usr/src/linux-2.2.5% grep SYSRQ arch/i386/defconfig .config arch/i386/defconfig:CONFIG_MAGIC_SYSRQ=y .config:CONFIG_MAGIC_SYSRQ=y viper:/usr/src/linux-2.2.5% uname -a Linux some.inet.address 2.2.5-15 #1 Mon Apr 19 22:21:09 EDT 1999 i586 unknown In 2.2.5-22 kernel (the last version in updates/) arch/i386/defconfig has CONFIG_MAGIC_SYSRQ also enabled. The most interesting is that standard kernel distribution (linux-2.2.5.tar.gz) doesn't have SYSRQ enabled -- it was set to "y" by RedHat (probably during beta-testing), and is "y" for all architectures. So, those who use RedHat don't even have to say "Y" and decide if they are hackers or not -- the decision was made for them beforehand ;-). ___________________________________________________________________ Dmitry Yu. Bolkhovityanov | Novosibirsk, RUSSIA phone (383-2)-39-49-56 | The Budker Institute of Nuclear Physics | Lab. 5-13
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