Re: [RFC][PATCH 2/4] checkpoint/restart: x86 support

From: Jeremy Fitzhardinge
Date: Mon Aug 11 2008 - 12:08:29 EST


Dave Hansen wrote:
On Sun, 2008-08-10 at 07:55 -0700, Jeremy Fitzhardinge wrote:
Struct pt_regs is not ABI, and can (and has) changed on x86. It's not suitable for a checkpoint structure because it only contains the registers that the kernel trashes, not all usermode registers (on i386, it leaves out %gs, for example). asm-x86/ptrace-abi.h does define stuff that's fixed in stone; it expresses it in terms of a register array, with constants defining what element is which register.

Thanks for the explanation.

I just want to reduce the coding and maintenance burden here. Xen must
do this for partition mobility, right? Does it define all its own
stuff?

You mean save/restore/migrate? Yes, it defines all its own stuff. Checkpoint-resume on a whole VM is a rather simpler operation than a subset of processes.

J

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