On 02/16/2016 12:00 PM, Oliver Neukum wrote:
Hi,
you make USB_APPLEDISPLAY depend on HAS_IOMEM.
I am afraid you got it the wrong way round. There
is really no reason for a high level USB driver
to access memory.
Alright, let's have a look. The warning I was fixing in this patch was:
warning: (USB_APPLEDISPLAY) selects BACKLIGHT_LCD_SUPPORT which has
unmet direct dependencies (HAS_IOMEM)
The problem is that USB_APPLEDISPLAY has 'select BACKLIGHT_LCD_SUPPORT',
but BACKLIGHT_LCD_SUPPORT has a dependency on HAS_IOMEM:
menu "Graphics support"
depends on HAS_IOMEM
...
source "drivers/video/backlight/Kconfig"
So this means that you are able to enable USB_APPLEDISPLAY even though
technically the Kconfig language doesn't support/allow it.
Looking at the "Graphics support" dependency on HAS_IOMEM, this was
added in the same patch that disabled USB for UML in the first place:
commit e25df1205f37c7bff3ab14fdfc8a5249f3c69c82
Author: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Date: Thu May 10 15:45:57 2007 +0200
[S390] Kconfig: menus with depends on HAS_IOMEM.
Add "depends on HAS_IOMEM" to a number of menus to make them
disappear for s390 which does not have I/O memory.
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
...in other words, I am inclined to agree with you that adding the
dependency for USB_APPLEDISPLAY is wrong and the "Graphics support" menu
should not depend on HAS_IOMEM in the first place.
That said, until the "Graphics support" dependency gets fixed or the
S390 commit gets reverted completely (I don't know if that's an option),
I think it's probably better to keep my commit to fix the warning --
without my patch series to enable USB on UML _all_ USB options have an
implicit (and incorrect) dependency on HAS_IOMEM.
Does that seem fair to you?
Vegard
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