Re: [PATCH][next] scsi: scsi_debug: make read-only arrays static const

[Christophe JAILLET]

Le 29/07/2025 à 21:49, Colin King (gmail) a écrit :
> On 29/07/2025 18:45, Christophe JAILLET wrote:
> > Le 29/07/2025 à 08:49, Colin Ian King a écrit :
> > > Don't populate the read-only arrays on the stack at run time, instead
> > > make them static const. Also reduces overall size.
> > >
> > > before:
> > >     text       data        bss        dec        hex    filename
> > >   367439      89582       5952     462973      7107d    drivers/scsi/ 
> > > scsi_debug.o
> > >
> > > after:
> > >     text       data        bss        dec        hex    filename
> > >   365847      90702       5952     462501      70ea5    drivers/scsi/ 
> > > scsi_debug.o
> >
> > Hi,
> >
> > out of curiosity, any idea why 'data' increase?
>
> Because the arrays are being stored in the data section rather than on 
> the stack.

Even when const is used?

See [1] for example, adding const moves the size from data to text.
I would expect the same with your patch.

CJ

[1]: 
https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=86b0fc4b2b45a78cbdc11873bc596d140eff390c

> > All my constification patches lead to data reduction.
> >
> > > (gcc 14.2.0, x86-64)
> >
> > (same kind of behavior with 15.1.1)
> >
> >
> > CJ