[SLOF] [PATCH slof] fdt: Pass the resulting device tree to QEMU

[Segher Boessenkool]

On Tue, Oct 03, 2017 at 03:33:16PM +1100, Alexey Kardashevskiy wrote:
> On 03/10/17 02:12, Segher Boessenkool wrote:
> > On Mon, Oct 02, 2017 at 10:09:52PM +1100, Alexey Kardashevskiy wrote:
> >>> : fdt-c,  fdt-here  1 fdt-allot  c! ;
> >>> : fdt-align  fdt-here 4 #aligned fdt-here - ; \ or fill with zeroes?
> >>> : fdt-str, ( str len -- )  fdt-here over fdt-allot  swap move ;
> >>> : fdt-ztr, ( str len -- )  fdt-str,  0 fdt-c, ;
> >>> \ and now use   fdt-str, fdt-align   instead of   false fdt-struct-add
> >>> \ and just  fdt-ztr, fdt-align   for   true fdt-struct-add
> > 
> > I don't see it, but I haven't tested it either, just typed it :-)
> > 
> > : fdt-str, ( str len -- )
> >   fdt-here over ( str len fhere len )
> >   fdt-allot ( str len fhere )
> >   swap ( str fhere len )
> >   move ( -- )
> > ;
> > 
> > Looks fine to me?

Well,

: fdt-str, ( str len -- )  dup fdt-allot  fdt-here swap move ;

is probably clearer :-)

> >>> The properties are not a linked list, but a Forth wordlist.  This is a)
> >>> faster, because wordlists are optimised a bit, say ten times faster; and
> >>> b) this allows use to run any code we want to get a property, not just
> >>> lookups of static data.  From property.fs:
> >>>
> >>> \ Words on the property list for a node are actually executable words,
> >>> \ that return the address and length of the property's data.  Special
> >>> \ nodes like /options can have their properties use specialized code to
> >>> \ dynamically generate their data; most nodes just use a 2CONSTANT.
> >>
> >> Hm. I wonder if it makes sense to rewrite fdt-properties using this.
> > 
> > You might need to make a case-sensitive wordlist search then?
> 
> I have no idea, any example? I'll probably skip this bit this time though.

Currently deep down all wordlists use string=ci (that is, case-insensitive
string compare).  I think for the FDT string table you will want case-
sensitive instead.

(When searching the Forth dictionaries Open Firmware requires case-
insensitive; and upper case is not allowed in property names, so doing
a case-insensitive search works there, too (at least in practice, even
though people *do* use upper case in property names).

One option is to set some global flag before finding a word; another is
to have a separate word for case-sentive finding; yet another is to set
a flag in the wordlist itself saying if it should be case-sensitive.
That last one is probably the most useful for other purposes, too.


Segher