On Wed, Sep 30, 2020 at 01:25:14PM +0200, Daniel Vetter wrote:
On Wed, Sep 30, 2020 at 12:56 PM Peilin Ye yepeilin.cs@gmail.com 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@gmail.com 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.
Ick, don't do that, the first trick of having them start out with an increased reference count is the best way here. Makes the code simpler and no special cases for the tear-down path.
thanks,
greg k-h