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Re: [Qemu-devel] [qemu-s390x] [PATCH v4 2/2] s390x: Enable KVM huge page
From: |
Janosch Frank |
Subject: |
Re: [Qemu-devel] [qemu-s390x] [PATCH v4 2/2] s390x: Enable KVM huge page backing support |
Date: |
Thu, 2 Aug 2018 08:53:18 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 01.08.2018 18:47, Thomas Huth wrote:
> On 08/01/2018 03:19 PM, Janosch Frank wrote:
>> +static int kvm_s390_configure_mempath_backing(KVMState *s)
>> +{
>> + size_t path_psize = qemu_mempath_getpagesize(mem_path);
>> +
>> + if (path_psize == 4 * KiB)
>> + return 0;
>
> Missing curly braces.
urgh, right, this is not the kernel.
>
>> + if (path_psize != 1 * MiB) {
>> + error_report("Memory backing with 2G pages was specified, "
>> + "but KVM does not support this memory backing");
>
> May I suggest to use a text that rather matches the condition of the
> if-statement (just in case there will be other sizes in the future...),
> e.g. "Memory backing is only supported for 1 MiB huge pages" or
> something similar.
>
> Thomas
>
That's actually the gist of it. s390 supports 4k, 1M and 2G and looking
at the POP I don't see a big chance of having any more sizes, as there
are not a lot of software bits left and adding support in OSs is a pain.
Also don't hold your breath for 2G, it would need a rewrite of gmap.c.
Also this is more explicit.
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