On Wed, Oct 31, 2001 at 05:13:23PM -0800, Donald A. Dade wrote: > Hello, > > I understand that Linux 2.4 has one TSS per CPU now, and that task > switching is done in software. From looking at the relevant pieces of > code, though, I cannot discern exactly where the state of all the > registers is saved/loaded. I see a subset being being saved and loaded > in switch_to(). What is it about x86 that allows this to work? It switches stacks - It is called via an interrupt, so all of the registers will have been saved on the stack, switch_to() just switches the stack (and saves registers that havn't been pushed on interrupt handler entry) The TSS is only used for the io protection bitmap now, I believe. This cannot be done anywhere else -- Mark Zealey (aka JALH on irc.openprojects.net: #zealos and many more) mark@zealos.org mark@itsolve.co.uk UL++++>$ G!>(GCM/GCS/GS/GM) dpu? s:-@ a16! C++++>$ P++++>+++++$ L+++>+++++$ !E---? W+++>$ N- !o? !w--- O? !M? !V? !PS !PE--@ PGP+? r++ !t---?@ !X---? !R- b+ !tv b+ DI+ D+? G+++ e>+++++ !h++* r!-- y-- (www.geekcode.com) - Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ IRC Channel: irc.openprojects.net / #kernelnewbies Web Page: http://www.kernelnewbies.org/
