linux-kernel - Re: kernel boot fail with efi earlyprintk (bisected)

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Message-ID: <20140822100456.GB1877@darkstar.nay.redhat.com>
Date:	Fri, 22 Aug 2014 18:04:56 +0800
From:	Dave Young <dyoung@...hat.com>
To:	"Zheng, Lv" <lv.zheng@...el.com>
Cc:	Matt Fleming <matt@...sole-pimps.org>,
	"Fleming, Matt" <matt.fleming@...el.com>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devel@...ica.org" <devel@...ica.org>,
	"lenb@...nel.org" <lenb@...nel.org>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"Moore, Robert" <robert.moore@...el.com>,
	"Lv Zheng (zetalog@...il.com)" <zetalog@...il.com>
Subject: Re: kernel boot fail with efi earlyprintk (bisected)

On 08/22/14 at 05:55am, Zheng, Lv wrote:
> Hi,
> 
> I checked the arch/x86/platform/efi/early_printk.c.
> In early_efi_scroll_up(), 2 mapping entries will be used for the src/dst screen buffer.
> In drivers/acpi/acpica/tbutils.c, we've improved the early table loading code in acpi_tb_parse_root_table().
> We now need 2 mapping entries:
> 1. One mapping entry is used for RSDT table mapping. Each RSDT entry contains an address for another ACPI table.
> 2. For each entry in RSDP, we need another mapping entry to map the table to perform necessary check/override before installing it.
> 
> When acpi_tb_parse_root_table() prints something through EFI earlyprintk console, we'll have 4 mapping entries used.
> The current 4 slots setting of early_ioremap() seems to be too small for such a use case.
> 
> I'm not 100% sure if this is the cause.
> If it's the cause and we think both of the mappings are reasonable, we can simply increase the FIX_BITMAPS_SLOTS defined in arch/x86/include/asm/fixmap.h.

Hmm, will give see if I can do more debug, I can try what you suggested.

Thanks
Dave
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