Messages in this thread | | | Date | Mon, 28 Apr 2014 18:51:18 -0500 | Subject | Re: [PATCH] arm64: fixmap: fix missing sub-page offset for earlyprintk | From | Rob Herring <> |
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On Mon, Apr 28, 2014 at 1:50 PM, Marc Zyngier <marc.zyngier@arm.com> wrote: > Commit d57c33c5daa4 (add generic fixmap.h) added (among other > similar things) set_fixmap_io to deal with early ioremap of devices. > > More recently, commit bf4b558eba92 (arm64: add early_ioremap support) > converted the arm64 earlyprintk to use set_fixmap_io. A side effect of > this conversion is that my virtual machines have stopped booting when > I pass "earlyprintk=uart8250-8bit,0x3f8" to the guest kernel. > > Turns out that the new earlyprintk code doesn't care at all about > sub-page offsets, and just assumes that the earlyprintk device will > be page-aligned. Obviously, that doesn't play well with the above example. > > Further investigation shows that set_fixmap_io uses __set_fixmap instead > of __set_fixmap_offset. A fix is to introduce a set_fixmap_offset_io that > uses the latter, and to remove the superflous call to fix_to_virt > (which only returns the value that set_fixmap_io has already given us). > > With this applied, my VMs are back in business. Tested on a Cortex-A57 > platform with kvmtool as platform emulation. > > Cc: Mark Salter <msalter@redhat.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > --- > arch/arm64/kernel/early_printk.c | 6 ++---- > include/asm-generic/fixmap.h | 3 +++ > 2 files changed, 5 insertions(+), 4 deletions(-)
This will be fixed already in 3.16 with my earlycon series[1] if this is not taken for 3.15.
Probably still a good addition for fixmap.
Rob
[1] https://lkml.org/lkml/2014/4/18/573
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