WSLg update on 1-5-2021 - BSD / WSL

David Chisnall theraven at
Fri May 7 13:31:42 UTC 2021

On 07/05/2021 11:17, Rozhuk Ivan wrote:
> On Thu, 6 May 2021 10:57:16 +0100
> David Chisnall <theraven at> wrote:
>> Whether Microsoft or the FreeBSD project should do the work really
>> comes down to who has more to gain.  Windows 10 is installed on
>> around a 1.3 billion devices and any of these users can run Ubuntu
>> with a single click in the Microsoft Store, so it feels as if the
>> FreeBSD project has a lot to gain from being able to reach them.
> Make job for free - make more money for MS.
> Make win10 to support more features to increase windows value...

How much money?  'Making money' doesn't just mean money coming in, it 
means more money coming in than is going out.  Adding features to a 
product costs money.  How many people will buy Windows 10 if it has a 
good FreeBSD compatibility layer who wouldn't buy it without one?  I 
very much doubt that this is a sufficient number to cover the cost of 
the engineering work.

>> Microsoft, in contrast, is driven by requests from customers who
>> spend money on our products and services.
>> Around a hundred people
>> commented on the WSL issue to add FreeBSD support.
> Ok, do you job and add FBSD support to WSL.

First, this is nowhere near even related to my job.  I don't work on 
Windows, let alone WSL.

Second, I have already explained why this is not a sufficiently large 
market to impact engineering decisions.

>> If you assume
>> that 1% of people who want the feature commented, then this gives
>> around 10,000 folks who really want a FreeBSD equivalent of WSL.
> They give money to MS, they ask MS to do job for money.

They give money to MS, they get a Windows 10 license in return.  They 
are happy to buy Windows without a FreeBSD compat layer.  They are 
buying Windows on the basis of some subset of a large number of 
features.  The lack of a FreeBSD compat layer is not preventing them 
from buying Windows, they have not shown that this is the deal-breaker 

Microsoft, like any other POTS software vendor, will prioritise features 
that impact the most customers.  There are things on User Voice with 
tens or hundreds of thousands of votes and these tend to be prioritised. 
  Something with under a hundred votes is so niche that it's only going 
to be a target of investment if it impacts another product or service.

>> It's pretty hard to justify a feature in Windows that only 0.001% of
>> Windows users will use. If you want to change that arithmetic, then
>> next time your organisation is renewing M365 or Azure service
>> subscriptions, tell your sales rep that FreeBSD support is important
>> to your company.
> There is many other hosting services that have FBSD support.
> So this is MS/azure problem.

Azure already officially supports FreeBSD and we have contributed a load 
of code to improve that support over the years.  From the numbers I've 
seen, I strongly suspect that we've spent more on it than we've gained 
in revenue.

You are asking Microsoft to throw money at a thing that will definitely 
cost time and money (and comes with the associated opportunity cost, 
because developer time spent on this features is developer time not 
spent on other features) but with no clear indication that it will 
increase revenue.  Effectively, you are asking us to do work for free 
and you're also doing so quite rudely.

Personally, I'd love to have a FreeBSD compat layer.  The license would 
even make it possible to embed the FreeBSD kernel in Windows and so get 
the best aspects of WSL1 and WSL2.  From a business perspective; 
however, I can't argue that this would be a great use of engineer time. 
  There are a load of features that would positively impact a lot more 
users that would be higher priority.

If you want this to happen and you want Microsoft to do it, then you 
need to help people inside the company provide this business case. 
Things that don't help include:

  - I want it.
  - You suck for not doing it.
  - It would make you money in unspecified ways.

Things that do help include:

  - We are a FreeBSD shop with 1,000 workstations, we would switch to 
Windows on the desktop with this feature.
  - We are a large cloud customer with 10,000 VMs deployed, we would 
switch to Azure with this feature.
  - We are a Windows shop with a load of desktops but are planning to 
switch to Macs because we want a BSD-style userland.

If you just want it to happen, then you don't need Microsoft to do 
anything.  All of the code required to build a Linux system that 
integrates with WSL2 is open source and you can implement something 
compatible for FreeBSD.  You can probably even skip a bunch of the boot 
requirements by using Linux as a bootloader and having a tiny Linux 
image that just kexecs a FreeBSD kernel.


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