2020-04-12 02:53:40

by Dave Young

Subject: [PATCH] efi/earlycon: fix early printk for wider fonts

When I play with terminus fonts I noticed the efi early printk does
not work because the earlycon code assumes font width is 8.

Here add the code to adapt with larger fonts. Tested with all kinds
of kernel built-in fonts on my laptop. Also tested with a local draft
patch for 14x28 !bold terminus font.

Signed-off-by: Dave Young <[email protected]>
---
drivers/firmware/efi/earlycon.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

--- linux-x86.orig/drivers/firmware/efi/earlycon.c
+++ linux-x86/drivers/firmware/efi/earlycon.c
@@ -114,14 +114,16 @@ static void efi_earlycon_write_char(u32
const u32 color_black = 0x00000000;
const u32 color_white = 0x00ffffff;
const u8 *src;
- u8 s8;
- int m;
+ int m, n, bytes;
+ u8 x;

- src = font->data + c * font->height;
- s8 = *(src + h);
+ bytes = BITS_TO_BYTES(font->width);
+ src = font->data + c * font->height * bytes + h * bytes;

- for (m = 0; m < 8; m++) {
- if ((s8 >> (7 - m)) & 1)
+ for (m = 0; m < font->width; m++) {
+ n = m % 8;
+ x = *(src + m / 8);
+ if ((x >> (7 - n)) & 1)
*dst = color_white;
else
*dst = color_black;

2020-04-13 14:25:43

by Ard Biesheuvel

Subject: Re: [PATCH] efi/earlycon: fix early printk for wider fonts

On Sun, 12 Apr 2020 at 04:49, Dave Young <[email protected]> wrote:
>
> When I play with terminus fonts I noticed the efi early printk does
> not work because the earlycon code assumes font width is 8.
>
> Here add the code to adapt with larger fonts. Tested with all kinds
> of kernel built-in fonts on my laptop. Also tested with a local draft
> patch for 14x28 !bold terminus font.
>
> Signed-off-by: Dave Young <[email protected]>

Thanks Dave. I tested this with the 10x18 font, which is utterly
broken for efifb unless I apply this patch.

I'll queue this as a fix.




> ---
> drivers/firmware/efi/earlycon.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> --- linux-x86.orig/drivers/firmware/efi/earlycon.c
> +++ linux-x86/drivers/firmware/efi/earlycon.c
> @@ -114,14 +114,16 @@ static void efi_earlycon_write_char(u32
> const u32 color_black = 0x00000000;
> const u32 color_white = 0x00ffffff;
> const u8 *src;
> - u8 s8;
> - int m;
> + int m, n, bytes;
> + u8 x;
>
> - src = font->data + c * font->height;
> - s8 = *(src + h);
> + bytes = BITS_TO_BYTES(font->width);
> + src = font->data + c * font->height * bytes + h * bytes;
>
> - for (m = 0; m < 8; m++) {
> - if ((s8 >> (7 - m)) & 1)
> + for (m = 0; m < font->width; m++) {
> + n = m % 8;
> + x = *(src + m / 8);
> + if ((x >> (7 - n)) & 1)
> *dst = color_white;
> else
> *dst = color_black;
>

2020-05-22 18:34:31

by tip-bot2 for Alexey Makhalov

Subject: [tip: efi/urgent] efi/earlycon: Fix early printk for wider fonts

The following commit has been merged into the efi/urgent branch of tip:

Commit-ID: 8f592ada59b321d248391bae175cd78a12972223
Gitweb: https://git.kernel.org/tip/8f592ada59b321d248391bae175cd78a12972223
Author: Dave Young <[email protected]>
AuthorDate: Sun, 12 Apr 2020 10:49:27 +08:00
Committer: Ard Biesheuvel <[email protected]>
CommitterDate: Tue, 12 May 2020 12:29:45 +02:00

efi/earlycon: Fix early printk for wider fonts

When I play with terminus fonts I noticed the efi early printk does
not work because the earlycon code assumes font width is 8.

Here add the code to adapt with larger fonts. Tested with all kinds
of kernel built-in fonts on my laptop. Also tested with a local draft
patch for 14x28 !bold terminus font.

Signed-off-by: Dave Young <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ard Biesheuvel <[email protected]>
---
drivers/firmware/efi/earlycon.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c
index 5d4f847..a52236e 100644
--- a/drivers/firmware/efi/earlycon.c
+++ b/drivers/firmware/efi/earlycon.c
@@ -114,14 +114,16 @@ static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
const u32 color_black = 0x00000000;
const u32 color_white = 0x00ffffff;
const u8 *src;
- u8 s8;
- int m;
+ int m, n, bytes;
+ u8 x;

- src = font->data + c * font->height;
- s8 = *(src + h);
+ bytes = BITS_TO_BYTES(font->width);
+ src = font->data + c * font->height * bytes + h * bytes;

- for (m = 0; m < 8; m++) {
- if ((s8 >> (7 - m)) & 1)
+ for (m = 0; m < font->width; m++) {
+ n = m % 8;
+ x = *(src + m / 8);
+ if ((x >> (7 - n)) & 1)
*dst = color_white;
else
*dst = color_black;