Messages in this thread | | | Subject | Re: [PATCH] tools: usb: usbip: adding support for older kernel versions | From | shuah <> | Date | Mon, 25 Mar 2019 09:51:21 -0600 |
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On 3/18/19 12:23 PM, Brian Norris wrote: > On Sat, Mar 16, 2019 at 4:40 PM shuah <shuah@kernel.org> wrote: >> usbip tool is tied to the kernel version. This is reason why it is >> co-located with the usbip driver in the kernel sources. This is not >> a typical tool scenario to be able to use new tool on old kernels. >> >> I would like to understand the reasons for wanting to run new tool on >> old kernels. > > On Chromium OS, we ship more or less the same user space for a variety > of systems, but not all of those run the same kernel. That's not > exactly a novel concept -- many good tools are written such that they > degrade gracefully when running with reduced feature sets (e.g., older > kernels). While we are working on reducing the divergence and number > of kernels we ship, it's currently a fact of life that we have to > support multiple target kernel versions.
Thanks for the context for this change.
> > Is there a fundamental problem with VHCI such that it doesn't have a > stable ABI that tools can be written against? >
In general the ABI is stable.
+#define V3_18_STATUS_HEADER "prt sta spd bus dev socket local_busid"
What's your 3.18 kernel version? I think you are missing security fixes that prevent socket address leak in the status file.
+#define V4_4_STATUS_HEADER "prt sta spd dev sockfd local_busid" +#define V4_14_STATUS_HEADER "hub port sta spd dev sockfd local_busid"
The difference here is the high speed support. Let's find a better way to fix this than hard-coding kernel revisions in the tool.
> If stability is possible but you just don't care, then I guess we can > fork our own version... > > Or even worse, we could build N copies of usbip for N kernels. But we > don't do that for any other user space component. >
It might be easier to build N versions than maintaining the fork :)
In any case, let's find ways to fix the problem with a constructive approach.
thanks, -- Shuah
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