Messages in this thread | | | Date | Wed, 9 Dec 2015 20:14:11 +0100 | From | Borislav Petkov <> | Subject | Re: x86 fpu: command-line parameters broken post-FPU-rewrite |
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On Wed, Dec 09, 2015 at 09:32:10AM +0100, Ingo Molnar wrote: > > * Dave Hansen <dave.hansen@intel.com> wrote: > > > Hey Ingo, > > > > We were starting to look at reenabling XSAVES support and tried to use the > > 'noxsave' and 'noxsaves' kernel command-line options. The rewrite moved the FPU > > initialization to before we even are parsing command-line options, even the > > early_param()s. > > > > Do you have any preferences on how it gets fixed? > > > > The most obvious thing would be to just defer as much of the FPU setup as we can > > until after parse_early_param() has happened. The only other think I can think > > of doing would be to try to do some *really* early, simple, command-line parsing > > to look for 'noxsave' and friends. > > > > Thoughts? > > Hm, so given that having the FPU operational is key to a functioning kernel (and > other kernel subsystems may make use of FPU functionality), I'd rather bring > option parsing earlier than change the FPU setup sequence. FPU setup should be > done when we identify the CPU - not 'very late' as we used to.
We already have early cmdline parsing: arch/x86/lib/cmdline.c
See users for examples.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
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