Re: [PATCH v4 05/44] x86/boot: introduce struct boot_module

["Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>]

On 9/3/24 19:29, Andrew Cooper wrote:
> On 30/08/2024 10:46 pm, Daniel P. Smith wrote:
> > diff --git a/xen/arch/x86/include/asm/bootinfo.h 
> > b/xen/arch/x86/include/asm/bootinfo.h
> > index e785ed1c5982..844262495962 100644
> > --- a/xen/arch/x86/include/asm/bootinfo.h
> > +++ b/xen/arch/x86/include/asm/bootinfo.h
> > @@ -8,10 +8,16 @@
> >   #ifndef __XEN_X86_BOOTINFO_H__
> >   #define __XEN_X86_BOOTINFO_H__
> >   
> > +#include <xen/multiboot.h>
> >   #include <xen/types.h>
> >   
> > +struct boot_module {
> > +    module_t *early_mod;
> This could do with a /* Transitionary only */ comment.  In this patch
> it's not too bad, but it does get worse as new fields are added, before
> being removed.
Yep, can add a comment.

> I'd also drop the "early_" part.  I know it's the initial_images array
> we're converting, but "early_" doesn't convey any extra meaning, and it
> makes a number of lines get quite hairy.
I can drop it.

> > +};
> > +
> >   struct boot_info {
> >       unsigned int nr_mods;
> > +    struct boot_module *mods;
> struct boot_module modules[MAX_NR_BOOTMODS + 1];
>
> Probably at the end of the structure.  In turn it ...
I can move it here, though just to be clear, are you suggesting that it 
is kept at the end of the structure as more fields are added.
> >   
> >       const char *boot_loader_name;
> >       const char *cmdline;
> > diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> > index c6b45ced00ae..28fdbf4d4c2b 100644
> > --- a/xen/arch/x86/setup.c
> > +++ b/xen/arch/x86/setup.c
> > @@ -278,12 +278,17 @@ custom_param("acpi", parse_acpi_param);
> >   
> >   static const char *cmdline_cook(const char *p, const char *loader_name);
> >   
> > +/* Max number of boot modules a bootloader can provide in addition to Xen */
> > +#define MAX_NR_BOOTMODS 63
> > +
> >   static const module_t *__initdata initial_images;
> >   static struct boot_info __initdata *boot_info;
> >   
> > -static void __init multiboot_to_bootinfo(multiboot_info_t *mbi)
> > +static void __init multiboot_to_bootinfo(multiboot_info_t *mbi, module_t *mods)
> >   {
> >       static struct boot_info __initdata info;
> > +    static struct boot_module __initdata boot_mods[MAX_NR_BOOTMODS + 1];
> ... drops this static.
Will be dropped.

> > +    unsigned int i;
> >   
> >       info.nr_mods = mbi->mods_count;
> >   
> > @@ -303,6 +308,14 @@ static void __init multiboot_to_bootinfo(multiboot_info_t *mbi)
> >           info.mmap_length = mbi->mmap_length;
> >       }
> >   
> > +    info.mods = boot_mods;
> > +
> > +    for ( i=0; i < info.nr_mods; i++ )
> i = 0
Ack.

> > +        boot_mods[i].early_mod = &mods[i];
> > +
> > +    /* map the last mb module for xen entry */
> > +    boot_mods[info.nr_mods].early_mod = &mods[info.nr_mods];
> The comment is good, but note how this is just one extra iteration of
> the loop, (so use <= for the bound).
I will move the comment above the loop and adjust the condition.

v/r,
dps