Re: I request inclusion of SAS Transport Layer and AIC-94xx into the kernel
From: Luben Tuikov (luben_tuikov_at_adaptec.com)
Date: 09/30/05
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Date: Fri, 30 Sep 2005 16:32:31 -0400 To: andrew.patterson@hp.com
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
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- Previous message: Rajesh Shah: "Re: [Pcihpd-discuss] Re: ACPI problem with PCI Express Native Hot-plug driver"
- In reply to: Andrew Patterson: "Re: I request inclusion of SAS Transport Layer and AIC-94xx into the kernel"
- Next in thread: Andrew Patterson: "Re: I request inclusion of SAS Transport Layer and AIC-94xx into the kernel"
- Reply: Andrew Patterson: "Re: I request inclusion of SAS Transport Layer and AIC-94xx into the kernel"
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