Messages in this thread | | | From | John Alvord <> | Subject | Re: copy to user | Date | Tue, 20 Nov 2001 13:28:29 -0800 |
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On Tue, 20 Nov 2001 20:54:42 +0000 (WET), Luis Miguel Correia Henriques <umiguel@alunos.deis.isec.pt> wrote:
>The reason that I need it to spend CPU time is that I'm developing a fault >injector. The purpose of a fault injection tool is, as you could imagine, >to test some critical systems and it's capacity to recover from fails. The >reason for changing the code of a process is that process must be delayed >but without leaving the CPU - everything must look like nothing wrong is >happening, except for other processes that are waiting for something from >the delayed process... > >Maybe I should have explained this before... sorry. > >I suppose now you can understand why SIGSTOP won't work. Hope you can help >me :) > >About using udelay... this soluction seemed fine to me at first but if I >hang the CPU with udelay the scheduler will no be doing it's job (isn't >it?). This would give me even more intrusiveness (another requirement: the >less intrusiveness as possible). > >Isn't there any doubt that copy_to_user can handle my problem? When I use >it to change CS, this function returns the correct number of bytes (and no >error) but, when I try to read... the old data is still there. I suppose >there is a page/segment protection against writing to CS, isn't it?
Maybe the kernel logic could lock the relevent page so it couldn't be paged out...
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