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Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targ
From: |
Sean Bruno |
Subject: |
Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets |
Date: |
Mon, 21 Mar 2016 07:52:44 -0700 |
User-agent: |
Mozilla/5.0 (X11; FreeBSD amd64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
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On 03/21/16 02:11, Alex Bennée wrote:
>
> Peter Maydell <address@hidden> writes:
>
>> On 20 March 2016 at 19:20, Sean Bruno <address@hidden>
>> wrote:
>>> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512
>>>
>>> aarch64 targets are now failing to build on i386 hosts due to
>>> missing __atomic_load_8() calls since this commit:
>>>
>>> https://github.com/qemu/qemu/commit/a0aa44b488b3601415d55041e4619aef5f3a4ba8#diff-c143d686899ae51d7b927d9c682e12fd
>>>
>>>
>>>
I'm unsure if Linux is disabling aarch64 targets for i386 hosts or if
>>> this commit works "just fine" on Linux hosts right now, as it
>>> doesn't work with clang or gcc.
>>
>> I think it just works on most Linux 32-bit architectures because
>> the compiler support can inline a suitable atomic op (there is
>> one case where it doesn't, which I think is PPC32).
>>
>> In any case, we mustn't use atomics on types larger than the host
>> pointer type, because it's not portable enough. Paolo or Alex,
>> can you have a look at this?
>
> I'll get a BSD up and running and check. What is triggering the
> __atomic_load_8 though?
>
>>
Specifically, its the atomic_read of vm_clock_warp_start in cpus.c:
114 /***********************************************************/
115 /* guest cycle counter */
116
117 /* Protected by TimersState seqlock */
118
119 static bool icount_sleep = true;
120 static int64_t vm_clock_warp_start = -1;
121 /* Conversion factor from emulated instructions to virtual clock
ticks. */
122 static int icount_time_shift;
....
339 static void icount_warp_rt(void)
340 {
341 /* The icount_warp_timer is rescheduled soon after
vm_clock_warp_start
342 * changes from -1 to another value, so the race here is okay.
343 */
344 if (atomic_read(&vm_clock_warp_start) == -1) {
345 return;
346 }
347
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- [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Sean Bruno, 2016/03/20
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Peter Maydell, 2016/03/20
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Alex Bennée, 2016/03/21
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets,
Sean Bruno <=
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Alex Bennée, 2016/03/21
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Paolo Bonzini, 2016/03/21
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Sean Bruno, 2016/03/22
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Alex Bennée, 2016/03/22
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Sean Bruno, 2016/03/28
- Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Sean Bruno, 2016/03/31
Re: [Qemu-devel] [FreeBSD] Host build i386 failing to build aarch64 targets, Paolo Bonzini, 2016/03/21