[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] For running Xen on a 32-way system
Here is a patch to get Xen running on a 32-way Unisys ES7000 system. Please note that this patch alone is not sufficient to do this. You will also need the clustered APIC patch that I will be submitting soon. But since this patch was to a general area in Xen I decided to submit it separately. I think this patch will be required to get Xen running on any system that has more than 16 CPUs. Here are the following things I did along with the questions I have: 1. I bumped up NR_CPUS to 32 in include/asm-x86/config.h. Is this value high enough? I know there are some big systems out there. Should this be bumped up to 64 or 128? 2. Increasing the value of NR_CPUS caused the system to die while bringing up the 17th CPU. Digging into this I found that the GDT limit was hard coded for a 16-way. To fix this I had to increase the value of NR_RESERVED_GDT_ENTRIES in include/public/arch-x86_xx.h. (I am assuming that NR_RESERVED_GDT_ENTRIES is set by the formula 2*NR_CPUS+8 for x86_32 and 4*NR_CPUS+8 for x86_64) It seems that there is no correlation between the two headers, arch-x86_xx.h and config.h. For now I have explained the correlation with a comment. Should this correlation be checked somehow at compile time? 3. Should the GDT limit be checked while the system is booting against the number of CPUs so that the system dies with an appropriate message rather than just dying while trying to bring up the NR_CPUS+1th CPU? Will this patch be useful or would it be over kill? Signed off by Aravindh Puthiyaparambil <aravindh.puthiyaparambil@xxxxxxxxxx> Attachment:
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