On Wednesday 04 October 2006 20:53, Horms wrote: > On Fri, Sep 29, 2006 at 12:48:19PM +0900, Horms wrote: > > On Wed, Sep 27, 2006 at 11:52:12AM +0200, Tristan Gingold wrote: > > > Linux and xen call efi in real mode if set_virtual_address_map fails. > > > You may add an option in both xen and linux to force calling efi in real mode. > > > This should be really simple and you will be able to make progress. > > > > I took a stab at forcing the call to stay in real mode, > > by simply replacing the call to set_virtual_address_map with > > a return. This should both prevent the mapping from occuring, > > and force the kernel to use the real mode variants of the calls. > > > > Unfortunately, the boot fails with the following log. > > A bit of investigation has found that is it dying in > > > > SAL_CALL() > > called by: ia64_sal_cache_flush() > > called by: ia64_sal_cache_flush() > > called by: ia64_sal_init() > > > > Well, when I say dying in, its probably more accurate to say, > > never returning from. I haven't been following this thread and don't know whether this is related, but someone here is seeing an MCA in this early SAL_CACHE_FLUSH call. I haven't looked at it in detail yet, but apparently it happens because we're making the call in virtual mode before we have completely set up the TLB and VHPT. > > I'm a bit of a loss to know why this is occuring. Though > > I do wonder if SAL (and in this case indrectly PAL) calls are > > are running into trouble by runing in real mode without > > set_virtual_address_map() having being called. SAL_CACHE_FLUSH is one of a few SAL calls that invoke PAL procedures, and they can't be used in virtual mode until the OS registers the virtual address of PAL (see SAL spec section 9.1.1). > It turns out that this was indeed the case, and running SAL calls > in physical mode (regardless of if EFI is making physical or virtual > mode calls) seems to fix this boot failure. Though I am yet to determin > it it solves the xen->linux, linux->xen kexec problem. In general (I'm not speaking to xen or kexec), I think we want to run SAL calls in virtual mode. It looks like we have a problem with the specific SAL_CACHE_FLUSH call above, but we should be able to fix that specific problem without changing how we do other SAL calls. Bjorn - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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