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Re: [Qemu-devel] [PATCH] docs: add blkdebug block driver documentation
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH] docs: add blkdebug block driver documentation |
Date: |
Mon, 22 Sep 2014 11:05:42 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.0 |
On 09/22/2014 03:20 AM, Stefan Hajnoczi wrote:
> The blkdebug block driver is undocumented. Documenting it is worthwhile
> since it offers powerful error injection features that are used by
> qemu-iotests test cases.
>
> This document will make it easier for people to learn about and use
> blkdebug.
>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
> docs/blkdebug.txt | 142
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 142 insertions(+)
> create mode 100644 docs/blkdebug.txt
>
> diff --git a/docs/blkdebug.txt b/docs/blkdebug.txt
> new file mode 100644
> index 0000000..7e616e0
> --- /dev/null
> +++ b/docs/blkdebug.txt
> @@ -0,0 +1,142 @@
No worse than many other files in this directory for omitting copyright
and license information (which means it inherits the default of GPLv2+
from the top-level).
> +
> +Rules can be placed in a .ini file:
Choice of article depends on whether you pronounce it "a dot-innie" or
"an eye-en-eye" file.
> +
> + $ cat blkdebug.conf
This file suffix is not '.ini'. So the idea is more that it is a
configuration file that uses '.ini' style parsing, and not that it is an
actual '.ini' file.
> + [inject-error]
> + event = "read_aio"
> + errno = "28"
> +
> +This rule fails all aio read requests with ENOSPC (28).
Eeesh - we are really tying things to host-dependent errno values?
Might be worth a paragraph explaining that ENOSPC is not always 28. Or
a design improvement to the setup to allow symbolic naming of the
desired actions. Or both.
> +
> + errno - the POSIX errno value to return when a request matches this rule
> +
Again, POSIX doesn't proscribe errno values, just symbolic names; and
those names differ in values across different OS.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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