* Re: xen on suse 9.3 and software raid [not found] ` <20050512135235.GC31317@bytesex> @ 2005-05-12 14:28 ` Gerd Knorr 2005-05-12 15:25 ` Re: [Xen-users] " Keir Fraser 0 siblings, 1 reply; 2+ messages in thread From: Gerd Knorr @ 2005-05-12 14:28 UTC (permalink / raw) To: Robbie Dinn; +Cc: xen-devel, xen-users, agruen [ adding xen-devel to Cc: ] > Just loading the raid6 module in a xen domain makes my > machine oops, log below. I'd guess it's because the > module attempts to use mmx within the kernel, which is > a bit tricky because you have to save/restore userspace > fp state for that. Could be a corner case which simply > doesn't work with xen. Confirmed, the faulting instruction is a attempt to access cr0, right here: static inline unsigned long raid6_get_fpu(void) { unsigned long cr0; preempt_disable(); asm volatile("mov %%cr0,%0 ; clts" : "=r" (cr0)); return cr0; } (which is called by raid6_before_mmx, which in turn is called by raid6_mmx1_gen_syndrome, both calls not visible in the trace because they are inlined). Ideas how to fix that? Other than just disabling raid6? Can that code be replaced with xen hypercalls? fsave & frestore are also used btw. It's all in drivers/md/raid6x86.h Gerd -- -mm seems unusually stable at present. -- akpm about 2.6.12-rc3-mm3 ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Re: [Xen-users] xen on suse 9.3 and software raid 2005-05-12 14:28 ` xen on suse 9.3 and software raid Gerd Knorr @ 2005-05-12 15:25 ` Keir Fraser 0 siblings, 0 replies; 2+ messages in thread From: Keir Fraser @ 2005-05-12 15:25 UTC (permalink / raw) To: Gerd Knorr; +Cc: xen-users, xen-devel, agruen On 12 May 2005, at 15:28, Gerd Knorr wrote: > (which is called by raid6_before_mmx, which in turn is called by > raid6_mmx1_gen_syndrome, both calls not visible in the trace > because they are inlined). > > Ideas how to fix that? Other than just disabling raid6? Can > that code be replaced with xen hypercalls? fsave & frestore > are also used btw. It's all in drivers/md/raid6x86.h This is a known issue with Xen 2.0, already fixed in unstable (by emulating the privileged instructions). There are three options here: 1. Live with it. Disable raid6 in Xen 2.0 and wait for upgrade to forthcoming Xen 3.0. 2. Backport some of the privileged-instruction emulation to Xen 2.0. 3. Patch the raid6x86.h for Xen 2.0 to do hypercalls rather than priv instructions. I think either options 1 or 2 would be best. Backporting the relevant bits of the instruction decoder and emulator from the unstable repository would not be very difficult, if this is a big show-stopper for anyone. -- Keir ^ permalink raw reply [flat|nested] 2+ messages in thread
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2005-05-12 14:28 ` xen on suse 9.3 and software raid Gerd Knorr
2005-05-12 15:25 ` Re: [Xen-users] " Keir Fraser
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