Re: [PATCH v2] xen/arm: Add 0x prefix when printing memory size in construct_domU

[Ayan Kumar Halder <ayankuma@xxxxxxx>]

Hi Julien,

I have a clarification.

On 05/01/2023 09:26, Julien Grall wrote:
> CAUTION: This message has originated from an External Source. Please 
> use proper judgment and caution when opening attachments, clicking 
> links, or responding to this email.
>
> Hi Stefano,
>
> On 04/01/2023 23:47, Stefano Stabellini wrote:
> > On Tue, 3 Jan 2023, Michal Orzel wrote:
> > > Printing memory size in hex without 0x prefix can be misleading, so
> > > add it. Also, take the opportunity to adhere to 80 chars line length
> > > limit by moving the printk arguments to the next line.
> > >
> > > Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
> > > ---
> > > Changes in v2:
> > >   - was: "Print memory size in decimal in construct_domU"
> > >   - stick to hex but add a 0x prefix
> > >   - adhere to 80 chars line length limit
> > Honestly I prefer decimal but also hex is fine.
> decimal is perfect for very small values, but as we print the amount in
> KB it will become a big mess. Here some examples (decimal first, then
> hexadecimal):
>
>   512MB: 524288 vs 0x80000
>   555MB: 568320 vs 0x8ac00
>   1GB: 1048576 vs 0x100000
>   512GB: 536870912 vs 0x20000000
>   1TB: 1073741824 vs 0x40000000
>
> For power of two values, you might be able to find your way with
> decimal. It is more difficult for non power of two unless you have a
> calculator in hand.
>
> The other option I suggested in v1 is to print the amount in KB/GB/MB.
> Would that be better?
>
> That said, to be honest, I am not entirely sure why we are actually
> printing in KB. It would seems strange that someone would create a guest
> with memory not aligned to 1MB.
For RTOS (Zephyr and FreeRTOS), it should be possible for guests to have 
memory less than 1 MB, isn't it ?
- Ayan

> So I would consider to check the size is 1MB-aligned and then print the
> value in KB. This will remove one order of magnitude and make the value
> more readable in decimal.
>
> Cheers,
>
> --
> Julien Grall