Re: [PATCH] kvm tools: Make the whole guest memory mergeable

[Zang Hongyong <zanghongyong@huawei.com>]

于 2011/12/16,星期五 15:23, Sasha Levin 写道:
> On Fri, 2011-12-16 at 15:02 +0800, Zang Hongyong wrote:
>> 于 2011/12/16,星期五 13:50, Sasha Levin 写道:
>>> On Fri, 2011-12-16 at 09:01 +0800, zanghongyong@huawei.com wrote:
>>>> If a guest's ram_size exceeds KVM_32BIT_GAP_START, the corresponding kvm tool's
>>>> virtual address size should be (ram_size + KVM_32BIT_GAP_SIZE), rather than ram_size.
>>> You're right.
>>>
>>> There are more places than just the madvise() code which make the same
>>> error you've spotted (for example, the memslot allocation code), so
>>> instead of trying to fix all of them I'd suggest to just update ram_size
>>> in kvm__arch_init() before allocating everything - that should fix all
>>> of them at once.
>>>
>> Yes. There are other scenarios with the same error.
>> However ram_size sometimes means real guest ram size, and sometimes 
>> means virtual address
>> size of kvm tool's user space. Shall we define a new variable?
> Let's keep it simple. If the user requests more than RAM than
> KVM_32BIT_GAP_START just increase it by KVM_32BIT_GAP_SIZE, this way
> mapped size == guest size always (we can madvise(MADV_DONTNEED) the gap
> in the mmapped ram).
>
> Since a user which requests more than KVM_32BIT_GAP_START will have to
> be on 64bit host anyway, there shouldn't be any issue with that.
>
Do you mean increase *kvm->ram_size* by KVM_32BIT_GAP_SIZE?
but sometimes kvm->ram_size stands for guest physical ram size (for
example in kvm__init_ram() code).