Messages in this thread | | | Date | Tue, 13 Mar 2007 16:57:47 +0100 | From | Andi Kleen <> | Subject | Re: _proxy_pda still makes linking modules fail |
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On Tue, Mar 13, 2007 at 05:23:52PM +1100, Rusty Russell wrote: > On Tue, 2007-03-13 at 08:59 +1100, Rusty Russell wrote: > > On Mon, 2007-03-12 at 10:48 +0100, Andi Kleen wrote: > > > > Rusty's pda->per_cpu patch will deal with this once and for all; have > > > > > > Not on x86-64. > > > > Indeed. Perhaps it's time I join the modern world and compile a 64-bit > > kernel... > > > > Will prepare patches, > > No, I don't think I will. The PDA concept has gone too far in x86-64 to > be undone. In particular, it's been put in GCC 4.1 for > CONFIG_CC_STACKPROTECTOR, which assumes %gs:40 will give the stack > canary.
Yes that was always ugly, but I don't know a better way.
> For the record: the PDA should never have existed, that's what percpu > vars were supposed to be for. Something went wrong here 8(
PDA predates per cpu.
> The ideal solution has always been to use __thread, but no architecture > has yet managed it (I tried for i386, and it quickly caused unbearable
I tried it too, but __thread is hopeless for kernel code
> pain). On x86-64 that uses "%fs" on x86-64, not "%gs" as the kernel > does, but I might try that if I feel particularly masochistic soon...
Then swapgs wouldn't work anymore (there is no swapfs)
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