sysfs: runtime byteorder detection #1872
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t-8ch
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I like it :-) |
| @@ -639,9 +651,9 @@ static void load_xinfo_from_proc_inet_L3(ino_t netns_inode, const char *proc_fil | |||
| sock->class = class; | |||
| sock->inode = (ino_t)inode; | |||
| sock->netns_inode = netns_inode; | |||
| inet->local_addr = local_addr; | |||
| inet->local_addr = kernel32_to_cpu(byteorder, local_addr); | |||
| tcp->local_port = local_port; | |||
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I think we need kernel16_to_cpu(byteorder, local_port);.
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It actually works without it.
IIRC the kernel always uses network-endianness for the port.
The inconsistency between address and port feels very much like a bug. But there's nothing to be done about it.
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OK, if I good understand, we need to wait for changes in Linus' tree. |
karelzak
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Indeed. For now I dropped the alternative filesystem specification as it is an unnecessary burden to carry around during the coordination process with the kernel. FYI the file has now moved to |
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The kernelpatch has been picked up by Greg and should end up in Linux 6.2 |
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@karelzak To adapt the tests for lscpu all the dumps need the file The alternative would be to move from archives to plain directories. This would make the diffs cleaner. |
t-8ch
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I guess the change is backwardly compatible ;-), so the tests without We need to update the script tests/ts/lscpu/mk-input.sh to gather cpu_byteorder too. |
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Yes it will work without the file. Do we want to update a bunch of binary archives or unpack them first? |
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The dumps already contain obsolete things but want to be compatible with these old kernels/dumps, so it makes sense to keep the old dumps unchanged. It would be better to create a new dump with the new kernel and add it as x86_64-linux-6.2.tar.gz or so (or something more exotic if you have ...). |
This can be used to read the file /sys/kernel/cpu_byteorder from an alternative root-directory.
t-8ch
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This can be used to skip tests that require that the machine executing the tests has the same byteorder as the test executable. Useful for tests emulated with qemu-user.
It contains the new file /sys/kernel/cpu_byteorder that lscpu will use to read the actual byteorder.
t-8ch
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The necessary kernel changes have been merged as https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/kernel/ksysfs.c?id=d3d76fbde1c456a6d19991baa99ea8c2d6e6696f |
This is a proof-of-concept that makes use of a new procfs file[0] to detect the byteorder of a running kernel at runtime.
The advantage is that
lsfdandlscpuwork correctly even in the face of emulation.Cc @karelzak @masatake
[0] https://git.sr.ht/~t-8ch/linux/log/proc-byteorder