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

[Michael Chang]

On Thu, Mar 29, 2018 at 11:02:51AM +0200, Daniel Kiper wrote:
> 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?

We did have discussion about the patch before it was submitted upstream but I
did not ask for RB as well. 

> 
> 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.

As I did not ask for it, it has to be removed.

Thanks for notifying this.
Michael

> 
> > ---
> > 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
> 
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