[9fans] Nix/regen: multiboot flags

[9fans] Nix/regen: multiboot flags

[tlaronde]

In l32p.s, the multiboot flags in the the mbi are set as

$0x00010007

but I don't find flags definitions relative to the higher word,
neither in the multiboot v1 spec, nor in the enum in multiboot.c. They
are all limited to the two lowest bytes.

What is the purpose of the:

$0x00010007
      ^

Typo?
-- 
        Thierry Laronde <tlaronde +AT+ kergis +dot+ com>
                     http://www.kergis.com/
                    http://kertex.kergis.com/
Key fingerprint = 0FF7 E906 FBAF FE95 FD89  250D 52B1 AE95 6006 F40C

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Re: [9fans] Nix/regen: multiboot flags

[Ron Minnich]

all that does is set the lowest two bytes, which is fine.

On Tue, Jan 28, 2025 at 6:09 AM <tlaronde@kergis.com> wrote:
> 
> In l32p.s, the multiboot flags in the the mbi are set as
> 
> $0x00010007
> 
> but I don't find flags definitions relative to the higher word,
> neither in the multiboot v1 spec, nor in the enum in multiboot.c. They
> are all limited to the two lowest bytes.
> 
> What is the purpose of the:
> 
> $0x00010007
>       ^
> 
> Typo?
> --
> Thierry Laronde <tlaronde +AT+ kergis +dot+ com>
>              http://www.kergis.com/
>             http://kertex.kergis.com/
> Key fingerprint = 0FF7 E906 FBAF FE95 FD89  250D 52B1 AE95 6006 F40C

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Re: [9fans] Nix/regen: multiboot flags

[Paul Lalonde]

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The multiboot specification says: If bit 16 in the ‘flags’ word is set,
then the fields at offsets 12-28 in the Multiboot header are valid, and the
boot loader should use them instead of the fields in the actual executable
header to calculate where to load the OS image.

I believe they are valid in this case.  These include the load address for
the kernel and the bit depth of the display, found at l32p.s:37,44

Paul

On Tue, Jan 28, 2025 at 6:09 AM <tlaronde@kergis.com> wrote:

> In l32p.s, the multiboot flags in the the mbi are set as
> 
> $0x00010007
> 
> but I don't find flags definitions relative to the higher word,
> neither in the multiboot v1 spec, nor in the enum in multiboot.c. They
> are all limited to the two lowest bytes.
> 
> What is the purpose of the:
> 
> $0x00010007
>       ^
> 
> Typo?
> --
> Thierry Laronde <tlaronde +AT+ kergis +dot+ com>
>              http://www.kergis.com/
>             http://kertex.kergis.com/
> Key fingerprint = 0FF7 E906 FBAF FE95 FD89  250D 52B1 AE95 6006 F40C

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[-- Attachment #2: Type: text/html, Size: 2969 bytes --]

Re: [9fans] Nix/regen: multiboot flags

[tlaronde]

On Tue, Jan 28, 2025 at 07:45:02AM -0800, Paul Lalonde wrote:
> The multiboot specification says: If bit 16 in the ?flags? word is set,
> then the fields at offsets 12-28 in the Multiboot header are valid, and the
> boot loader should use them instead of the fields in the actual executable
> header to calculate where to load the OS image.
> 
> I believe they are valid in this case.  These include the load address for
> the kernel and the bit depth of the display, found at l32p.s:37,44
> 

Thanks for the explanations!

> On Tue, Jan 28, 2025 at 6:09?AM <tlaronde@kergis.com> wrote:
> 
> > In l32p.s, the multiboot flags in the the mbi are set as
> > 
> > $0x00010007
> > 
> > but I don't find flags definitions relative to the higher word,
> > neither in the multiboot v1 spec, nor in the enum in multiboot.c. They
> > are all limited to the two lowest bytes.
> > 
> > What is the purpose of the:
> > 
> > $0x00010007
> >       ^
> > 
> > Typo?
> > --
> > Thierry Laronde <tlaronde +AT+ kergis +dot+ com>
> >              http://www.kergis.com/
> >             http://kertex.kergis.com/
> > Key fingerprint = 0FF7 E906 FBAF FE95 FD89  250D 52B1 AE95 6006 F40C

-- 
        Thierry Laronde <tlaronde +AT+ kergis +dot+ com>
                     http://www.kergis.com/
                    http://kertex.kergis.com/
Key fingerprint = 0FF7 E906 FBAF FE95 FD89  250D 52B1 AE95 6006 F40C

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