[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [Patch V3 14/15] xen: allow more than 512 GB of RAM for 64 bit pv-domains
On 05/27/2015 07:05 PM, David Vrabel wrote: On 27/05/15 17:25, David Vrabel wrote:On 20/04/15 06:23, Juergen Gross wrote:64 bit pv-domains under Xen are limited to 512 GB of RAM today. The main reason has been the 3 level p2m tree, which was replaced by the virtual mapped linear p2m list. Parallel to the p2m list which is being used by the kernel itself there is a 3 level mfn tree for usage by the Xen tools and eventually for crash dump analysis. For this tree the linear p2m list can serve as a replacement, too. As the kernel can't know whether the tools are capable of dealing with the p2m list instead of the mfn tree, the limit of 512 GB can't be dropped in all cases. This patch replaces the hard limit by a kernel parameter which tells the kernel to obey the 512 GB limit or not. The default is selected by a configuration parameter which specifies whether the 512 GB limit should be active per default for domUs (domain save/restore/migration and crash dump analysis are affected). Memory above the domain limit is returned to the hypervisor instead of being identity mapped, which was wrong anyway. The kernel configuration parameter to specify the maximum size of a domain can be deleted, as it is not relevant any more.Something in this patch breaks the hvc console in my test domU. kernel BUG at /local/davidvr/work/k.org/tip/drivers/tty/hvc/hvc_xen.c:153 Which suggests the hvc driver mapped the wrong console ring frame.Sorry, it's patch #13 (xen: move p2m list if conflicting with e820 map) that seems to be bad. I think I've found the reason: the console frame isn't being marked as "reserved" any more. With moving the p2m list I had to change the call of memblock_reserve() for it. Before that patch this call covered the p2m list, the start_info page, the xenstore page and the console page. I added a memblock_reserve() for start_info, but failed to do so for xenstore and console. I'll modify the patch and respin. I have to check why I didn't hit this issue. Maybe my test machine was too large and the memory in question didn't get reused until my test was finished. Thanks for testing, Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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