Subject: [PATCH] Correct description of /proc/sys/kernel/random/entropy_avail

Subject: [PATCH] Correct description of /proc/sys/kernel/random/entropy_avail

[Jon Jensen]

Patch against Git HEAD, based on others' comments on the web and empirical 
observation just reading the file repeatedly.

It contains the number of bits of currently available entropy,
not always the pool size of 4096.
---
  man4/random.4 |    4 ++--
  1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/man4/random.4 b/man4/random.4
index 2307e07..b097b6d 100644
--- a/man4/random.4
+++ b/man4/random.4
@@ -177,9 +177,9 @@ and can be changed to any value for which an algorithm is available.
  The choices are 32, 64, 128, 256, 512, 1024, or 2048.
  .TP
  Linux 2.6:
-This file is read-only, and gives the size of the entropy pool in
+This file is read-only, and gives the amount of available entropy in
  .IR bits .
-It contains the value 4096.
+The value will range from 0 to 4096 in a standard kernel.
  .RE
  .LP
  The file
-- 
1.7.1.86.g0e460

-- 
Jon Jensen
End Point Corporation
http://www.endpoint.com/

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Re: Subject: [PATCH] Correct description of /proc/sys/kernel/random/entropy_avail

[Michael Kerrisk (man-pages)]

Hello Jon,

On 23 July 2010 at 02:18, Jon Jensen <jon-O9fzpki4YnJWk0Htik3J/w@public.gmane.org> wrote:
> Patch against Git HEAD, based on others' comments on the web and empirical
> observation just reading the file repeatedly.
>
> It contains the number of bits of currently available entropy,
> not always the pool size of 4096.
> ---
>  man4/random.4 |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/man4/random.4 b/man4/random.4
> index 2307e07..b097b6d 100644
> --- a/man4/random.4
> +++ b/man4/random.4
> @@ -177,9 +177,9 @@ and can be changed to any value for which an algorithm
> is available.
>  The choices are 32, 64, 128, 256, 512, 1024, or 2048.
>  .TP
>  Linux 2.6:
> -This file is read-only, and gives the size of the entropy pool in
> +This file is read-only, and gives the amount of available entropy in
>  .IR bits .
> -It contains the value 4096.
> +The value will range from 0 to 4096 in a standard kernel.
>  .RE
>  .LP
>  The file
> --
> 1.7.1.86.g0e460

Your email fell on the floor a few years ago. Sorry about that...

Long after the fact, I've applied a slightly different patch:

diff --git a/man4/random.4 b/man4/random.4
index d4bd03f..4dbf585 100644
--- a/man4/random.4
+++ b/man4/random.4
@@ -213,9 +213,8 @@ The files in the directory
 device:
 .TP
 .I entropy_avail
-This read-only file gives the available entropy.
-Normally, this will be 4096 (bits),
-a full entropy pool.
+This read-only file gives the available entropy, in bits.
+This will be a number in the range 0 to 4096.
 .TP
 .I poolsize
 This file

Cheers,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: Subject: [PATCH] Correct description of /proc/sys/kernel/random/entropy_avail

[Jon Jensen]

On Tue, 13 Dec 2016, Michael Kerrisk (man-pages) wrote:

> Your email fell on the floor a few years ago. Sorry about that...
>
> Long after the fact, I've applied a slightly different patch:
>
> diff --git a/man4/random.4 b/man4/random.4
> index d4bd03f..4dbf585 100644
> --- a/man4/random.4
> +++ b/man4/random.4
> @@ -213,9 +213,8 @@ The files in the directory
> device:
> .TP
> .I entropy_avail
> -This read-only file gives the available entropy.
> -Normally, this will be 4096 (bits),
> -a full entropy pool.
> +This read-only file gives the available entropy, in bits.
> +This will be a number in the range 0 to 4096.
> .TP
> .I poolsize
> This file

Your version looks great. Glad to have it fixed! I've handled a few 
patches many years after the fact myself, so I can chuckle about it from 
both sides of the transaction. :)

Thanks,
Jon

-- 
Jon Jensen
End Point Corporation
https://www.endpoint.com/
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Re: Subject: [PATCH] Correct description of /proc/sys/kernel/random/entropy_avail

[Michael Kerrisk (man-pages)]

Hi Jon,

On 13 December 2016 at 20:20, Jon Jensen <jon-O9fzpki4YnJWk0Htik3J/w@public.gmane.org> wrote:
> On Tue, 13 Dec 2016, Michael Kerrisk (man-pages) wrote:
>
>> Your email fell on the floor a few years ago. Sorry about that...
>>
>> Long after the fact, I've applied a slightly different patch:
>>
>> diff --git a/man4/random.4 b/man4/random.4
>> index d4bd03f..4dbf585 100644
>> --- a/man4/random.4
>> +++ b/man4/random.4
>> @@ -213,9 +213,8 @@ The files in the directory
>> device:
>> .TP
>> .I entropy_avail
>> -This read-only file gives the available entropy.
>> -Normally, this will be 4096 (bits),
>> -a full entropy pool.
>> +This read-only file gives the available entropy, in bits.
>> +This will be a number in the range 0 to 4096.
>> .TP
>> .I poolsize
>> This file
>
>
> Your version looks great. Glad to have it fixed! I've handled a few patches
> many years after the fact myself, so I can chuckle about it from both sides
> of the transaction. :)

:-}

Your patch arrived at the worst possible moment. 2010 was a hard year.
In fact, the only reason I found the patch again was that I swept my
mailbox for patches relating to random(4), because in the last release
of man-pages[1] (yesterday), random(4) and related pages had massive
updates, and I thought I just better go and check if there was
anything old that that was related and that I had missed in my inbox.
Yours was the only relevant mail :-).

Cheers,

Michael

[1] http://linux-man-pages.blogspot.de/2016/12/man-pages-409-is-released.html

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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