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Re: [Qemu-devel] [PATCH v5 22/45] postcopy: OS support test
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v5 22/45] postcopy: OS support test |
Date: |
Mon, 30 Mar 2015 16:09:27 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 30/03/2015 16:07, Dr. David Alan Gilbert wrote:
>>> > >
>> >
>> > You would just require new _installed_ kernel headers. Then you can use
>> > linux/userfaultfd.h and syscall.h (the latter from glibc, includes
>> > asm/unistd.h to get syscall numbers).
>> >
>> > linux-headers/ is useful for APIs that do not require system calls, or
>> > for APIs that are extensible. However, if a system call is required
>> > (and mandatory) it's simpler to just use installed headers.
> OK, so then I could check for ifdef __NR_userfault and then
> do the include and I think that would be safe.
I think it's okay. First include syscall.h, then include
linux/userfaultfd.h under #ifdef.
> Although then what's the best way to tell people to try it out
> without an updated libc?
They don't need an updated libc, just an updated kernel. syscall.h is
just a wrapper around Linux headers.
Paolo
> Or is it best to modify ./configure to detect it?