Re: [Xen-devel] [PATCH] Improve Dom0-less documentation

[Julien Grall <julien.grall@xxxxxxx>]

Hello,

On 7/8/19 1:35 PM, Viktor Mitin wrote:
> Updated configuration example according to arm64
> and added more cases about known xl limitations.
dom0less is not an arm64 specific feature. It also works on arm32, and 
therefore the docs should work for both cases. However...
> Signed-off-by: Viktor Mitin <viktor_mitin@xxxxxxxx>
> ---
>   docs/features/dom0less.pandoc | 29 +++++++++++++++++++++--------
>   1 file changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/docs/features/dom0less.pandoc b/docs/features/dom0less.pandoc
> index e076e3739e..961813696f 100644
> --- a/docs/features/dom0less.pandoc
> +++ b/docs/features/dom0less.pandoc
> @@ -62,19 +62,19 @@ device tree adding a node under /chosen as follows:
>   
>       domU1 {
>           compatible = "xen,domain";
> -        memory = <0x20000>;
> +        memory = <0x0 0x20000>; >           cpus = 1;
>           vpl011;
>   
>           module@2000000 {
>               compatible = "multiboot,kernel", "multiboot,module";
> -            reg = <0x2000000 0xffffff>;
> +            reg = <0x0 0x2000000 0x0 0xffffff>;
... nothing on arm64 impose #address-cells = 2 and #size-cells = 2. The 
problem here is the two properties are missing in the node domU1.
>               bootargs = "console=ttyAMA0";
>           };
>   
>           module@30000000 {
>               compatible = "multiboot,ramdisk", "multiboot,module";
> -            reg = <0x3000000 0xffffff>;
> +            reg = <0x0 0x3000000 0x0 0xffffff>;
>           };
>       };
>   
> @@ -90,12 +90,25 @@ Limitations
>   Domains started by Xen at boot time currently have the following
>   limitations:
>   
> -- They cannot be properly shutdown or rebooted using xl. If one of them
> -  crashes, the whole platform should be rebooted.
> -
>   - Some xl operations might not work as expected. xl is meant to be used
> -  with domains that have been created by it. Using xl with domains
> -  started by Xen at boot might not work as expected.
> +  with domains that have been created by it:
> +
> +    -> Using xl with domains started by Xen at boot might not work
> +       as expected.
> +
> +    -> They cannot be properly shutdown or rebooted using xl.
> +       If one of them crashes, the whole platform should be rebooted.
> +
> +    -> 'xl console' command will not switch console input.
'xl console' does not switch input. The command will attach to the 
domain's console.
But I would not view this as a restriction, they are domains created by 
Xen (similar to Dom0) and therefore they are all managed by Xen and some 
of the commands may not work.
> +       Type 'CTRL-a' three times to switch input in case of dom0less mod
This is confusing to read. You will switch input to the next "domain". 
This could be Xen or one of the domain.
Also, a user is allowed to configure the key sequence to switch input.
So it would be better to write something like: "pressing the Xen
"conswitch" (Ctrl-A by default) three times"

> +
> +    -> 'xl list' prints the list of domains.
> +       However DomU names are shown as '(null)' in the list. For example:
This is not specific to 'xl list'. Domains created by Xen will have no 
name at boot. Domain-0 has a name thanks to the helper xen-init-dom0 
called at boot by the initscript.
If you want to have name here, then you will have to create the xenstore 
node associated.
> +
> +        root@dom0:~# xl list
> +        Name                         ID   Mem VCPUs      State   Time(s)
> +        Domain-0                      0   256     4     r-----       6.2
> +        (null)                        1   256     1     -b----       1.7
>   
>   - The GIC version is the native version. In absence of other
>     information, the GIC version exposed to the domains started by Xen at
Cheers,

--
Julien Grall

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