Re: [PATCH 3/3] linux-user: Rewrite target_shmat

[Richard Henderson <richard.henderson@linaro.org>]

On 2/23/24 01:35, Ilya Leoshkevich wrote:
> On Thu, Feb 22, 2024 at 05:03:09PM -1000, Richard Henderson wrote:
>> Handle combined host and guest alignment requirements.
>> Handle host and guest page size differences.
>> Handle SHM_EXEC.
>>
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/115
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   linux-user/mmap.c | 146 ++++++++++++++++++++++++++++++++++------------
>>   1 file changed, 110 insertions(+), 36 deletions(-)
> 
> [...]
> 
>> -    /* find out the length of the shared memory segment */
>> +    /*
>> +     * Because we can't use host shmat() unless the address is sufficiently
>> +     * aligned for the host, we'll need to check both.
>> +     * TODO: Could be fixed with softmmu.
>> +     */
> 
> Are there any plans to introduce softmmu to qemu-user?

Long-term ones, yes.  There are *so* many places for which emulation doesn't quite work 
unless the host and guest page size match.  There are projects like asan which don't work 
unless the guest has a *very* specific memory layout, which often conflicts with the host.



r~