Re: Xen Compilation Error on Ubuntu 20.04

[Ayush Dosaj <ayushdosaj2313@gmail.com>]

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Hi Andrew, Xen Development team.

I compiled and installed Xen by appending -fcf-protection=none to CFLAGS on
Ubuntu 20.04 but it still crashes on startup.

On Wed, Apr 29, 2020 at 10:58 PM Ayush Dosaj <ayushdosaj2313@gmail.com>
wrote:

> Awesome, thanks!
>
> On Wed, Apr 29, 2020 at 10:55 PM Andrew Cooper <andrew.cooper3@citrix.com>
> wrote:
>
>> On 29/04/2020 18:17, Ayush Dosaj wrote:
>> > Hi Xen development team,
>> >
>> > I am Ayush. I compiled Xen Hypervisor from source on Ubuntu 20.04
>> > machine running on an intel-i9 CPU.
>> > I am getting compilation error due to the following two flags.
>> > Error: error: ‘-mindirect-branch’ and ‘-fcf-protection’ are not
>> compatible.
>> >
>> > Complete Error logs can be found at
>> https://paste.ubuntu.com/p/xvvyPnhW5c/
>> >
>> > And when I compiled Xen commenting the two flags in Rules.mk file, it
>> > compiles and installs properly but on boot-up i see a blank black screen
>> > and i am stuck there.
>>
>> That is a GCC bug (these options are actually fine in combination).  It
>> got fixed earlier today in master, and backported for GCC 9.4
>>
>> You can work around it by appending -fcf-protection=none to CFLAGS
>>
>> I wouldn't try editing the logic around -mindirect-branch, as that is
>> related to retpoline safety for Spectre v2, and probably relies on the
>> build matching the code.
>>
>> ~Andrew
>>
>
>
> --
> Ayush Dosaj
> VIT Vellore
>
>

-- 
Ayush Dosaj

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