Messages in this thread Patch in this message | | | Subject | [RFC][PATCH][TRIVIAL] System ACE fails in look for root devices | Date | Thu, 13 Oct 2011 13:02:42 +0200 | From | "Petr Cvek" <> |
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Hello,
I sent this mail some time ago, but nobody replied :-(.
I'm using microblaze linux on ML506 board and I found problem with SystemACE CF driver.
When xsysace driver is probed, and dts file does not include entry "port-number" (existence of line not actually tested) on line:
of_property_read_u32(dev->dev.of_node, "port-number", &id);
kernel fails to boot with this message:
<4>VFS: Cannot open root device "xsa2" or unknown-block(0,0) <4>Please append a correct "root=" boot option; here are the available partitions: <4>fff:ffff0 990864 xs` (driver?) <4> fff:ffff1 124960 xs`1 00000000-0000-0000-0000-000000000000 <4> fff:ffff2 865872 xs`2 00000000-0000-0000-0000-000000000000 <0>Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
(note xs` xs`1 xs`2 partition names)
So I've done some searching and found "ace->id" variable, which has value "-1". Because this value define letter of drive and is incremented by 'a', then with its value of -1, creates letter before 'a' thus '`'.
"ace->id" value is assigned in ace_probe function on line
of_property_read_u32(dev->dev.of_node, "port-number", &id); if (id < 0) id = 0;
This condition should prevents value to be less than zero, but is does not. It's because type, which is u32 few lines before, condition is never true. So I suggest changing it to int. Actually, there was patch some time ago, which has changed it into u32 (last patch for xsysace.c).
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=5d10302f46df1d9a85c34ea97f9b6c29e414482e
And finally here is my patch, which suggests changing this line back:
Test for signed value is never true, because of unsigned type.
From: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Petr Cvek <petr.cvek@tul.cz> --- diff --git a/drivers/block/xsysace.c b/drivers/block/xsysace.c index fb1975d..3ed920c 100644 --- a/drivers/block/xsysace.c +++ b/drivers/block/xsysace.c @@ -1155,7 +1155,7 @@ static int __devinit ace_probe(struct platform_device *dev) { resource_size_t physaddr = 0; int bus_width = ACE_BUS_WIDTH_16; /* FIXME: should not be hard coded */ - u32 id = dev->id; + int id = dev->id; int irq = NO_IRQ; int i;
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