On Tue, May 05, 2015 at 10:39:14AM +0100, Mark Rutland wrote:
On Mon, May 04, 2015 at 10:36:43AM +0100, Ian Campbell wrote:
On Mon, 2015-05-04 at 10:51 +0200, Hans de Goede wrote:
Hi,
On 02-05-15 15:21, Ian Campbell wrote:
On Fri, 2015-04-24 at 20:39 +0200, Hans de Goede wrote:
Linux-4.0 as shipped has a bug causing it to not boot if the end of memory is not aligned to a multiple of 2 MiB. For details see the linux-arm mailing list post titled: "Memory size unaligned to section boundary" http://www.spinics.net/lists/arm-kernel/msg413811.html
This is something which specifically hits the sunxi display driver because we carve out the exact needed framebuffer size at the top of mem, this commit works around this issue by aligning the carve out.
I'm afraid I don't like this, we shouldn't be working around Linux bugs in the firmware, especially when both are Free software. Lets just fix Linux and get the fix into the appropriate stable trees and in the meantime tell people to avoid this buggy kernel.
The problem with this sort of thing is that it is very hard to get rid of these workarounds, even once the underlying issue is fixed and we no longer care about the versions with the bug OS authors (including non-Linux OSes) can inadvertently come to rely on the quirky behaviour, (i.e. the work around masks other bugs). Hence we end up in a quirks-race as everyone works around the other parties last workaround.
If there is to be a workaround instead of a fix then it should be for Linux to align memory to 2MB boundaries if that is what it requires.
I can understand where you're coming from, the problem is that despite various mails to the arm kernel mailing list no one from the upstream kernel seems to be looking into this,
Mark, do you think you could find some cycles (not necessarily your own) to look at this, or perhaps you know the appropriate maintainers to ping?
I'll have another look and see if I can come up with a kernel patch. Perhaps proposing something (even if slightly wrong) will provoke people to respond.
For the benefit of anyone not on the Linux ARM kernel list there's now a patch addressing the issue [1].
Mark.
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-May/342210.html