On Thu, May 12, 2016 at 03:06:39PM +0200, Arnd Bergmann wrote: > On Thursday 12 May 2016 20:49:24 Zhangjian wrote: > > Hi, > > > > On 2016/5/12 17:21, Arnd Bergmann wrote: > > > On Thursday 12 May 2016 10:17:58 Catalin Marinas wrote: > > >> On Wed, May 11, 2016 at 09:30:07PM +0200, Arnd Bergmann wrote: > > >>> On Wednesday 11 May 2016 17:59:01 Catalin Marinas wrote: > > >>> > > >>> I don't think the shifts are a problem, the main downside would be > > >>> the limit to 44 bits of file offsets (16TB files), but it's also > > >>> unclear if that is a practical problem at all. If it is, we run > > >>> into the same problem on all other 32-bit architectures too. > > >> > > >> I hope people are seriously thinking of moving to an LP64 ABI if they > > >> have such large file offset needs. > > > > > > Good point. 44 bits of file size is certainly enough for mmap() > > > on a 32-bit task: you would only be able to map a very small fraction > > > of the file anyway, and if you want to map larger files, and should > > > move to 64-bit tasks long before this becomes a limitation. > > Hi, > > > > I apply the following patch in order to make use of the REAL mmmap2. LTP > > test pass in litle endian. mmap16 successful with segfault in big endian. > > > > BTW, I saw the similar code in tile, mips, microblaze and s390 compat. Should > > we merge these code into a common syscall wrapper? > > I think that's a good idea. The function used to be slightly different > for each architecture, but now it seems we have a significant number > of identical implementations that we could just merge them together > into one. > > sys_mmap_pgoff was originally introduced as the common implementation > and it reduced the amount of duplication a lot, but as its units > are based on PAGE_SIZE rather than hardwired 4096 bytes, it's > not as useful. > microblaze and mips (twice) are doing like this. And aarh32 as well, in arch/arm64/kernel/entry32.S In previous submissions it was a patch that shares aarch32 code to ilp32. If we decided turn around again, I think, we'd pick up that patch. The other option is to make this hack generic, as so many arches use it. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
