Re: [PATCH 3/5] tools/libs/foreignmemory: Fix PAGE_SIZE redefinition error

[Costin Lupu <costin.lupu@xxxxxxxxx>]

Hi Julien,

On 4/28/21 12:03 PM, Julien Grall wrote:
> Hi Costin,
> 
> On 27/04/2021 13:05, Costin Lupu wrote:
>>   tools/libs/foreignmemory/private.h | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/libs/foreignmemory/private.h
>> b/tools/libs/foreignmemory/private.h
>> index 1ee3626dd2..f3c1ba2867 100644
>> --- a/tools/libs/foreignmemory/private.h
>> +++ b/tools/libs/foreignmemory/private.h
>> @@ -10,11 +10,13 @@
>>   #include <xen/xen.h>
>>   #include <xen/sys/privcmd.h>
>>   -#ifndef PAGE_SHIFT /* Mini-os, Yukk */
>> +#ifndef PAGE_SHIFT
>>   #define PAGE_SHIFT           12
>>   #endif
>> -#ifndef __MINIOS__ /* Yukk */
>> +#ifndef PAGE_SIZE
>>   #define PAGE_SIZE            (1UL << PAGE_SHIFT)
>> +#endif
>> +#ifndef PAGE_MASK
>>   #define PAGE_MASK            (~(PAGE_SIZE-1))
>>   #endif
> 
> Looking at the usage, I believe PAGE_* are referring to the page
> granularity of Xen rather than the page granularity of the control
> domain itself.
> 
> So it would be incorrect to use the domain's page granularity here and
> would break dom0 using 64KB page granularity on Arm.
> 
> Instead, we should replace PAGE_* with XC_PAGE_*. If some of them are
> still referring to the control domain granularity, then we should use
> getpageshift() (Or equivalent) because the userspace shouldn't rely on a
> specific page granularity.

Yes, this makes sense. One thing I need to clarify: what does XC stand
for? I thought for some time it stands for Xen Control.

Thanks,
Costin