Re: [PATCH] linux-user: Update TASK_UNMAPPED_BASE for aarch64

[Aleksandar Markovic]

On Sat, Mar 14, 2020 at 11:45 AM Laurent Vivier <address@hidden> wrote:
>
> Le 14/03/2020 à 04:06, Aleksandar Markovic a écrit :
> > On Fri, Mar 13, 2020 at 1:28 AM Lirong Yuan <address@hidden> wrote:
> >>
> >> This change updates TASK_UNMAPPED_BASE (the base address for guest 
> >> programs) for aarch64. It is needed to allow qemu to work with Thread 
> >> Sanitizer (TSan), which has specific boundary definitions for memory 
> >> mappings on different platforms:
> >> https://github.com/llvm/llvm-project/blob/master/compiler-rt/lib/tsan/rtl/tsan_platform.h
> >>
> >> Signed-off-by: Lirong Yuan <address@hidden>
> >> ---
> >>  linux-user/mmap.c | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> >> index 8685f02e7e..e378033797 100644
> >> --- a/linux-user/mmap.c
> >> +++ b/linux-user/mmap.c
> >> @@ -184,7 +184,11 @@ static int mmap_frag(abi_ulong real_start,
> >>  }
> >>
> >>  #if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64
> >> +#ifdef TARGET_AARCH64
> >> +# define TASK_UNMAPPED_BASE  0x5500000000
> >
> > Hi, Lirong,
> >
> > Can you point from which line of the file you linked to did you
> > arrive to the value 0x5500000000?
> >
> > Second question: What about other targets?
>
> Personally, I prefer to not change the value for other targets if it is
> not required by someone that had some problems with the current value.
>
> It needs to be changed carefully and to be well tested after change.
>

Sure, but again, from where " 0x5500000000" comes from?

> Thanks,
> Laurent