linux-kernel - Re: [PATCH v2 10/10] x86, efi: EFI boot stub support

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Date:	Thu, 15 Sep 2011 10:04:38 +0200
From:	Maarten Lankhorst <m.b.lankhorst@...il.com>
To:	Matt Domsch <Matt_Domsch@...l.com>
CC:	Matt Fleming <matt@...sole-pimps.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Matthew Garrett <mjg@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mike Waychison <mikew@...gle.com>,
	Andi Kleen <andi@...stfloor.org>, jordan_hargrave@...l.com
Subject: Re: [PATCH v2 10/10] x86, efi: EFI boot stub support

Hey Matt,

On 09/15/2011 06:52 AM, Matt Domsch wrote:
> On Wed, Sep 14, 2011 at 11:07:58AM -0500, Matt Fleming wrote:
>> On Tue, 2011-09-13 at 16:33 +0200, Maarten Lankhorst wrote:
>>> This version seems to boot for me.
>> Yay! Thanks for testing.
>>
>>> Is it useful to add 32-bits support though?
>>> It seems that only some older versions of OSX use it. I could see if I can
>>> revive my mac mini, iirc it has 32-bits efi, or at least used to have.
>> 32-bit UEFI platforms do exist, so I think it's worth supporting them.
>>
>>> Do I need to pass anything to add it to efibootmgr?
>>>
>>> I tried something like this:
>>> echo "args" | efibootmgr -c -l '\vmlinuz.efi' -L 'Native EFI linux boot' -@ - -u -d /dev/sdb
>>>
>>> And it boots vmlinuz.efi, but the arguments I passed do not appear to
>>> have any effect.
>> No idea, I've never used efibootmgr. Let's add Matt Domsch to the
>> discussion (now Cc'd).
> Maarten, do you not see your 'args' in /proc/cmdline after booting the
> entry?  From reading this thread, that's what you should see.
>
> Can you provide an 'efibootmgr -v' and hexdump -C
> /sys/firmware/efi/vars/Boot*  to see the args are appended as expected
> in the boot variable in nvram?
>
> Adding Jordan Hargrave, who is maintainer for efibootmgr now.
Thanks, that helped. It looks like efibootmgr stores the arguments without converting it to UCS-2.

Patch below is a rough check for ascii, in which case it passes it unmodified.

After this 'args' is passed succesfully. :)

Should probably be folded in 10/10.

Signed-off-by: Maarten Lankhorst <m.b.lankhorst@...il.com>

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 6c34828..b24affb 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -619,12 +619,12 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
 	unsigned long cmdline;
 	u8 nr_entries;
 	u16 *s2;
-	u8 *s1;
+	u8 *s1, *s2_8;
 	int i;
 
 	hdr->type_of_loader = 0x21;
 
-	status = low_alloc(options_size, 1, &cmdline);
+	status = low_alloc(options_size+1, 1, &cmdline);
 	if (status != EFI_SUCCESS)
 		goto fail;
 
@@ -633,6 +633,14 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
 	/* Convert unicode cmdline to ascii */
 	s1 = (u8 *)(unsigned long)hdr->cmd_line_ptr;
 	s2 = (u16 *)options;
+	s2_8 = (u8*)options;
+	/* Assume the first byte is < 0x128 */
+	if (options_size > 1 && s2_8[1] && s2_8[1] < 0x80 && s2_8[0] < 0x80) {
+		s2 = NULL;
+		memcpy(s1, s2_8, options_size);
+		s1[options_size] = 0;
+		hdr->cmdline_size = options_size;
+	}
 
 	if (s2 && options_size) {
 		/* Skip first word, that's the kernel name */


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