Re: [PATCH 1/1] Fix PCIe LER when GRUB2 accesses non-enabled MMIO data from VGA

[Daniel Kiper]

On Wed, Mar 28, 2018 at 11:42:18AM -0500, address@hidden wrote:
> A GPU inserted into a PCIe I/O slot disappears during system startup.
> The problem centers around GRUB and a specific VGA init function in
> efi_uga.c.  This causes an LER (link error recorvery) because the MMIO
> memory has not been enabled before attempting access.
>
> The fix is to add the same coding used in other VGA drivers, specifically
> to add a check to insure that it is indeed a VGA controller.  And then
> enable the MMIO address space with the specific bits.
>
> Signed-off-by: Mike Travis <address@hidden>
> Reviewed-by: Michael Chang <address@hidden>
> Reviewed-by: Daniel Kiper <address@hidden>

Well, please do not add somebody RB tag if he/she did not explicitly
asked you to do that. And even in that case I was not able to look at
this patch in advance. So, my RB should not be here. Additionally, in
this situation I would like to ask if Michael approved his RB?

Anyway, patch LGTM except one nitpick. I will apply the patch, in a week or
so, with Michael's RB if I get confirmation that he approved it earlier.

> ---
> v1:change class to subclass, remove parens around "enable mem" code
> ---
>  grub-2.02/grub-core/video/efi_uga.c |   15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
>
> Index: grub-2.02/grub-core/video/efi_uga.c
> ===================================================================
> --- grub-2.02.orig/grub-core/video/efi_uga.c
> +++ grub-2.02/grub-core/video/efi_uga.c
> @@ -95,9 +95,18 @@ find_card (grub_pci_device_t dev, grub_p
>  {
>    struct find_framebuf_ctx *ctx = data;
>    grub_pci_address_t addr;
> +  grub_pci_address_t rcaddr;

This line should be together with the addr. I will fix it before
committing the patch.

Thank you for doing the work.

Daniel