On Ma, 15 feb 22, 12:41:28, John Hasler wrote: > Andrei POPESCU writes: > > When it loads a kernel or chain-loads another boot-loader it basically > > hands over control completely, > > Which is what DOS does. That was possibly not the best choice of words from my side. DOS was both very limited in capabilities and didn't implement any kind of access control or similar. Each application could basically take full control over the hardware[1], and any slightly advanced application did, because DOS didn't provide much for them to use[2]. But at any point the *same* instance of DOS was still in the RAM, and when exiting the application one would typically be back to the *same* DOS shell from where the application was started (unless it all crashed, of course). When GRUB is chain-loading another boot-loader or loads an OS it's also being completely evicted from RAM. The only way I can think of to "go back" without rebooting is for another boot-loader to chain-load the "initial" GRUB (which is a new instance of GRUB and in practice is not much different then rebooting). [1] This was probably the best breeding ground for computer viruses the bad guys could ever hope for, as they could "infect" (append themselves to) any file on the system and install themselves in the MBR. [2] Apparently this also made applications much harder to port to other OSes, which in practice worked as a sort of platform lock-in. Hope this explains, Andrei -- http://wiki.debian.org/FAQsFromDebianUser
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