Hi, please see below :-
Michael Blizek wrote:
> On 00:10 Sat 28 Jun , Abdul Basit wrote:
>
>> Hi Folks,
>>
>> I am trying to bring Xorg 7.x on PowerPC 440EPx Sequoia board, X is
>> configured to use sisfb for video and the sisfb is loaded properly in
>> kernel and registered as fb0, running X causes a machine check exception
>> / BUS error by kernel.
>>
>> The reason for that is in :-
>>
>> xorg/xorg-server/hw/xfree86/os-support/linux/lnx_video.c:558
>>
>> X is doing the following :-
>>
>> ----
>> ioBase_phys = syscall(__NR_pciconfig_iobase, 2, 0, 0);
>> fd = open("/dev/mem", O_RDWR);
>> if (ioBase == NULL) {
>> ioBase = (volatile unsigned char *)mmap(0, 0x20000,
>> PROT_READ | PROT_WRITE, MAP_SHARED,
>> ioBase_phys);
>> ----
>>
>
> Where do you pass the file descriptor to mmap?
>
>
sorry, cut and paste error, the correct one is :-
---
ioBase = (volatile unsigned char *)mmap(0, 0x20000,
PROT_READ | PROT_WRITE, MAP_SHARED, fd,
ioBase_phys);
---
>> the pci I/O memory in my case is 36-bits but the CPU is 32-bits so the
>> ioBase_phys is getting truncated as long is 32-bits and when later X try
>> to write to this address causes a BUS error.
>>
>> Since i know the ioBase_phys address which is 0x1E8000000, I could hard
>> code it but the mmap(..) offset size is 32-bits as well, so I could not
>> pass it as an offset.
>>
>> How would i pass a large offset to mmap on PPC32? is there any other way
>> to do it?
>>
>
> You can call mmap2 if the offset is a multiply of 4096. (see the manpage)
> -Michi
>
The type for offset in both mmap() and mmap2() if off_t which is
sizeof(off_t) = 4, infact i can not find mmap2 for powerpc in uclibc,
there is mmap()
which takes __off_t and mmap64() which takes __off64_t but that is only
enabled
if you use __FILE_OFFSET_SIZE=64 which i do not know if i turn it on
what are the consequences?
also internally mmap64() truncates the off64_t to off_t and a comment in
there
to implement architecture specific code in there.
Thanks,
~basit
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