On Wed, Sep 30, 2020 at 12:56 PM Peilin Ye <yepeilin.cs@xxxxxxxxx> wrote: > > On Wed, Sep 30, 2020 at 11:53:17AM +0200, Daniel Vetter wrote: > > On Wed, Sep 30, 2020 at 03:11:51AM -0400, Peilin Ye wrote: > > > On Tue, Sep 29, 2020 at 04:38:49PM +0200, Daniel Vetter wrote: > > > > On Tue, Sep 29, 2020 at 2:34 PM Peilin Ye <yepeilin.cs@xxxxxxxxx> wrote: > > > > > Ah, and speaking of built-in fonts, see fbcon_startup(): > > > > > > > > > > /* Setup default font */ > > > > > [...] > > > > > vc->vc_font.charcount = 256; /* FIXME Need to support more fonts */ > > > > > ^^^^^^^^^^^^^^^ > > > > > > > > > > This is because find_font() and get_default_font() return a `struct > > > > > font_desc *`, but `struct font_desc` doesn't contain `charcount`. I > > > > > think we also need to add a `charcount` field to `struct font_desc`. > > > > > > > > Hm yeah ... I guess maybe struct font_desc should be the starting > > > > point for the kernel internal font structure. It's at least there > > > > already ... > > > > > > I see, that will also make handling built-in fonts much easier! > > > > I think the only downside with starting with font_desc as the internal > > font represenation is that there's a few fields we don't need/have for > > userspace fonts (like the id/name stuff). So any helpers to e.g. print out > > font information need to make sure they don't trip over that > > > > But otherwise I don't see a problem with this, I think. > > Yes, and built-in fonts don't use refcount. Or maybe we can let > find_font() and get_default_font() kmalloc() a copy of built-in font > data, then keep track of refcount for both user and built-in fonts, but > that will waste a few K of memory for each built-in font we use... A possible trick for this would be to make sure built-in fonts start out with a refcount of 1. So never get freed. Plus maybe a check that if the name is set, then it's a built-in font and if we ever underflow the refcount we just WARN, but don't free anything. Another trick would be kern_font_get/put wrappers (we'd want those anyway if the userspace fonts are refcounted) and if kern_font->name != NULL (i.e. built-in font with name) then we simply don't call kref_get/put. -Daniel > > > > I think for vc_date->vc_font we might need a multi-step approach: > > > > - first add a new helper function which sets the font for a vc using > > > > an uapi console_font struct (and probably hard-coded assumes cnt == > > > > 256. > > > > > > But user fonts may have a charcount different to 256... But yes I'll try > > > to figure out how. > > > > Hm yeah, maybe we need a helper to give us the charcount then, which by > > default is using the magic negative offset. > > Ah, I see! :) > > > Then once we've converted everything over to explicitly passing charcount > > around, we can switch that helper. So something like > > > > int kern_font_charcount(struct kern_font *font); > > > > Feel free to bikeshed the struct name however you see fit :-) > > I think both `kern_font` and `font_desc` makes sense, naming is so > hard... > > > > > For first steps I'd start with demidlayering some of the internal > > > > users of uapi structs, like the console_font_op really shouldn't be > > > > used anywhere in any function, except in the ioctl handler that > > > > converts it into the right function call. You'll probably discover a > > > > few other places like this on the go. > > > > > > Sure, I'll start from this, then cleaning up these dummy functions, then > > > `vc_data`. Thank you for the insights! > > > > Please don't take this rough plan as fixed, it's just where I'd start from > > browsing the code and your analysis a bit. We'll probably have to adapt as > > we go and more nasty things turn up ... > > Sure, I'll first give it a try and see. Thank you! > > Peilin Ye > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
