Messages in this thread | | | Date | Tue, 21 May 2013 13:07:58 +0200 | Subject | Re: [PATCH] arm64: kernel: need extern variable 'screen_info' for related driver using. | From | Geert Uytterhoeven <> |
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On Tue, May 21, 2013 at 9:51 AM, Chen Gang <gang.chen@asianux.com> wrote: > On 05/21/2013 02:57 PM, Geert Uytterhoeven wrote: >> On Tue, May 21, 2013 at 5:15 AM, Chen Gang <gang.chen@asianux.com> wrote: >>>> >> I think it would be better if we added a something like >>>> >> CONFIG_HAVE_VGA_CONSOLE, which VGA_CONSOLE can then depend on. Architectures >>>> >> like x86 can then select the former, and we can remove the long list of >>>> >> architectures from the current option. >>> > >>> > I guess your meaning is: >>> > >>> > under arm64, actually, need not support 'VGA_CONSOLE', and 'screen_info' is useless. >>> > So better to define 'CONFIG_HAVE_VGA_CONSOLE' which 'VGA_CONSOLE' can depend on it, and in arm64, we do not define CONFIG_HAVE_VGA_CONSOLE. >>> > >>> > Is it correct ? >> No, you missed "and we can remove the long list of architectures from the >> current option". >> > > OK, thanks. > > Is it correct: "it is unnecessary to add 'screen_info' to the code, for > arm64 will never support 'VGA_CONSOLE'" ?
On arm (not (yet?) arm64), drivers/video/console/dummycon.c also uses screen_info. The default text mode resolution may come from atags.
>>> > If so, I recommend to add depend item for VGA_CONSOLE directly: >> I strongly support CONFIG_HAVE_VGA_CONSOLE. > > For me, I still recommend add 'ARM64' in the long list of architectures > for 'VGA_CONSOLE', I have 3 reasons, please check: > > a. current implementation only changes one area which only related with > arm64 and 'VGA_CONSOLE', but if use 'CONFIG_HAVE_VGA_CONSOLE', that will > touch many multiple platforms dependency, at least we need discuss about > it with multiple platforms guys for it, firstly.
Sure. But this can be one cleanup patch.
> b. We can find some cases to use CONFIG_HAVE_* as dpend on, but I can > not find any cases which let CONFIG_'samename' depend on > CONFIG_HAVE_'samename'.
A similar mechanism is used for PC-style floppy support, but the naming is different, cfr. drivers/block/Kconfig:
config BLK_DEV_FD tristate "Normal floppy disk support" depends on ARCH_MAY_HAVE_PC_FDC
so perhaps ARCH_MAY_HAVE_VGA?
PARPORT_PC could use the same mechanism.
> c. The original way still has effect, although it seems not quit > beautiful, but it is correct and still clear for readers, it is still > sustainable.
Most/every new architecture needs to add a depend to it.
BTW, I should have done this when sending out the patch to add CRIS to the list of dependencies...
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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