On 09/30/05 16:14, Andrew Patterson wrote: > > Yes you can, which is what I am trying to do. However, is that library > also available on Solaris and Windows? Is it up to date? These are the Is the kernel the latest one? Is it up to date? See? Same argument. >>>Note that a sysfs implementation has problems. Binary attributes are >>>discouraged/not-allowed. >> >>I've never heard that. Is this similar to the argument >>"The sysfs tree would be too deep?" > > >>From Documentation/filesystes/sysfs.txt > > "Attributes should be ASCII text files, preferably with only one value > per file. It is noted that it may not be efficient to contain only > value per file, so it is socially acceptable to express an array of > values of the same type. > > Mixing types, expressing multiple lines of data, and doing fancy > formatting of data is heavily frowned upon. Doing these things may get > you publically humiliated and your code rewritten without notice." I see this talk _only_ about non-binary attributes. Plus you have to admit: the SAS sysfs "smp_portal" binary attribute is very versatile: you completely control the expander from user space _if_ you can see it: It is almost like "point and click". I imagine there would be GUIs built on top of it, which would actually implement that "point, click, control". > My understanding is that sysfs is meant to be human-readable. I do not But `cat /sysfs/.../smp_portal` _is_ human readable. See? Its size is 0 bytes and when you read it you get 0 data read. > User space locking can only guarantee atomic operations in user space. And user space is the whole audience of this interface. > Not sure at the moment, can I guarantee this for the future? How far in the future? 1, 3, 6 months? 1, 3, 6 years? Plus if you need an attribute larger than 4K, you've got other problems to worry about. > There are as many as one would want. We now have 32 bit device numbers. > Old technology is fine as long as it works, especially if their is no > new technology to replace it. Note that I don't like the character > device solution either. What would really be nice is something that will > allow us to pass an arbitrary request buffer, and get an arbitrary > response buffer back in a single transaction, Here: /* User space lock */ fd = open(smp_portal, ...); write(fd, smp_req, smp_req_size); read(fd, smp_resp, smp_resp_size); close(fd); /* User space unlock */ > See above. This stuff works for trivial user-space apps. It will not > suffice for most storage management apps. Sorry but I completely fail to see this argument. How will it "fail for most storage managament apps"? Luben - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
