linux-kernel - Re: [PATCH] efi earlyprintk fix

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Message-ID: <20131108103648.GA2318@console-pimps.org>
Date:	Fri, 8 Nov 2013 10:36:48 +0000
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Dave Young <dyoung@...hat.com>
Cc:	matt.fleming@...el.com, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] efi earlyprintk fix

On Thu, 07 Nov, at 08:09:06PM, Dave Young wrote:
> Here is my debug message about the efifb params (all hex values):
> [    0.000000] efi fb lfb width: 280
> [    0.000000] efi fb lfb height: 1e0
> [    0.000000] efi fb lfb base: e0000000
> [    0.000000] efi fb lfb linelength: a00
> [    0.000000] efi fb font height: 10
> [    0.000000] efi fb font width: 8
> 
> The problem looks related to the pr_cont(), here is what I observed:
> [    0.000000] efi: EFI v2.00 by Lenovo
>                     ACPI=0xdabfe000  ACPI 2.0=0xdabfe014  SMBIOS=0xdaa9e000
> [    0.000000] efi: 
> 
> After relooking the code, below fix is more reasonable than my original one,
> But I still confused why it only happens on this machine.

Dave, could you try this patch?

---

diff --git a/arch/x86/platform/efi/early_printk.c b/arch/x86/platform/efi/early_printk.c
index 6599a0027b76..81b506d5befd 100644
--- a/arch/x86/platform/efi/early_printk.c
+++ b/arch/x86/platform/efi/early_printk.c
@@ -142,7 +142,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
 			efi_y += font->height;
 		}
 
-		if (efi_y + font->height >= si->lfb_height) {
+		if (efi_y + font->height > si->lfb_height) {
 			u32 i;
 
 			efi_y -= font->height;
-- 
Matt Fleming, Intel Open Source Technology Center
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