Re: [Xen-devel] [PATCH v2 for-4.7 5/6] xen/xsplice: add ELFOSABI_FREEBSD as a supported OSABI for payloads

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.05.16 at 11:48, <roger.pau@xxxxxxxxxx> wrote:
> On Tue, May 03, 2016 at 08:17:15AM -0600, Jan Beulich wrote:
>> >>> On 03.05.16 at 12:55, <roger.pau@xxxxxxxxxx> wrote:
>> > The calling convention used by the FreeBSD ELF OSABI is exactly the same as
>> > the the one defined by System V, so payloads with a FreeBSD OSABI should be
>> > accepted by the xsplice machinery.
>> 
>> Well, you realize that the ABI is more than just the calling convention?
>> I.e. your patch basically says ELFOSABI_NONE == ELFOSABI_FREEBSD,
>> in which case I wonder why the latter exists in the first place. Is there
>> a proper document somewhere describing everything the latter implies,
>> so that one can check whether for xSplice purposes such similar
>> treatment is indeed okay? Until then I'm afraid I'm opposed to this going
>> in.
> 
> The FreeBSD elf OSABI only has a meaning for userspace applications, it's 
> used by FreeBSD in order to detect if an application is native or if it 
> needs to be run in the linuxator (the Linux emulator, or any other emulator 
> that is available and matches the ELF OSABI specified in the binary FWIW).
> 
> THe only difference from SYSV to FreeBSD OSABI is the sysentvec that's 
> selected inside of the FreeBSD kernel (the ABI between the kernel and the 
> user-space application), but of course this doesn't apply to kernel code, 
> which is what Xen and the xsplice payloads are. Sadly this is not written 
> anywhere.

Well, okay, in that case I agree the patch should be fine.

Jan


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