Re: [PATCH 1/3] xen/arm64: head: Move earlyprintk 'hex' string to .rodata.str

[Julien Grall <julien@xxxxxxx>]

Hi Michal,

On 21/11/2023 17:18, Michal Orzel wrote:
> On 21/11/2023 18:04, Julien Grall wrote:
> > On 21/11/2023 17:00, Michal Orzel wrote:
> > > Hi Julien,
> > Hi,
> >
> > > On 21/11/2023 17:09, Julien Grall wrote:
> > > > Hi Michal,
> > > >
> > > > On 21/11/2023 09:45, Michal Orzel wrote:
> > > > > At the moment, the 'hex' string is placed right after the 'putn'
> > > > > function in the .text section. This is because of the limited range
> > > > > (+/- 1MB) of PC relative 'adr' instruction 'putn' uses. Modify it to use
> > > > > 'adr_l' instead (range extended to +/- 4GB) and move the string to
> > > > > .rodata.str. This way all the earlyprintk messages will be part of .rodata
> > > > > and the behavior will be consistent with what we already do on arm32.
> > > > This will be correct today, but I am actually thinking to move 'hex' to
> > > > .rodata.idmap so it can be used while we are on the 1:1 mapping and/or
> > > > temporary mapping.
> > > So you are planning on extending your series to also cover arm64?
> > It is not in my soonish plan. But you are arguing that this patch is for
> > consistency with arm32. This will not be after my series.
> Hmm, consistency was not the only reason for sending this patch. It's a 
> beneficial side effect
> given that putn implementations are very similar on arm32/arm64. 
> Are you saying that
> moving a string that is const from .text to .rodata is not a good change?
.rodata is better but I would rather prefer if this is moved to 
.rodata.idmap directly.
> > And I would not change arm64 just for consistency because I don't view
> > it as necessary. The boot code is already not the same.
> I don't recall trying to make the entire boot code consistent. But if there are 
> parts that
> are almost identical, I think symmetry is welcomed. It helps reading the code, 
> at least for me.
If you want symmetry, then I am happy to switch to .rodata.idmap. But I 
would rather not first move to .rodata and then in a month time switch 
to .rodata.idmap.
Cheers,

--
Julien Grall