[PATCH] fbdev: efifb: do not load efifb if PCI BAR has changed but not fixuped
Shixiong Ou
oushixiong1025 at 163.com
Fri Jun 27 08:07:50 UTC 2025
在 2025/6/26 18:31, Thomas Zimmermann 写道:
> Hi
>
> Am 26.06.25 um 11:49 schrieb oushixiong1025 at 163.com:
>> From: Shixiong Ou <oushixiong at kylinos.cn>
>>
>> [WHY]
>> On an ARM machine, the following log is present:
>> [ 0.900884] efifb: framebuffer at 0x1020000000, using 3072k, total
>> 3072k
>> [ 2.297884] amdgpu 0000:04:00.0:
>> remove_conflicting_pci_framebuffers: bar 0: 0x1000000000 -> 0x100fffffff
>> [ 2.297886] amdgpu 0000:04:00.0:
>> remove_conflicting_pci_framebuffers: bar 2: 0x1010000000 -> 0x10101fffff
>> [ 2.297888] amdgpu 0000:04:00.0:
>> remove_conflicting_pci_framebuffers: bar 5: 0x58200000 -> 0x5823ffff
>>
>> It show that the efifb framebuffer base is out of PCI BAR, and this
>
> The patch at
>
> https://patchwork.freedesktop.org/series/148057/
>
> is supposed to fix the problem. It has been merged with v6.16-rc1 as
> commit 2f29b5c23101 ("video: screen_info: Relocate framebuffers behind
> PCI bridges"). It is in your tree?
>
> Best regards
> Thomas
>
yeah, this patch is in my tree. but do not fix the problem.
this is some message:
kylin at kylin-pc:~$ dmesg | grep BAR
[ 0.688192] pci 0000:00:03.0: BAR 15: assigned [mem
0x1000000000-0x101fffffff 64bit pref]
[ 0.688200] pci 0000:00:00.0: BAR 0: assigned [mem
0x1020000000-0x10200fffff 64bit pref]
[ 0.688205] pci 0000:00:00.0: BAR 14: assigned [mem
0x58000000-0x580fffff]
[ 0.688210] pci 0000:00:01.0: BAR 0: assigned [mem
0x1020100000-0x10201fffff 64bit pref]
[ 0.688215] pci 0000:00:02.0: BAR 0: assigned [mem
0x1020200000-0x10202fffff 64bit pref]
[ 0.688221] pci 0000:00:02.0: BAR 14: assigned [mem
0x58100000-0x581fffff]
[ 0.688225] pci 0000:00:03.0: BAR 0: assigned [mem
0x1020300000-0x10203fffff 64bit pref]
[ 0.688231] pci 0000:00:03.0: BAR 14: assigned [mem
0x58200000-0x585fffff]
[ 0.688237] pci 0000:00:04.0: BAR 0: assigned [mem
0x1020400000-0x10204fffff 64bit pref]
[ 0.688243] pci 0000:00:05.0: BAR 0: assigned [mem
0x1020500000-0x10205fffff 64bit pref]
[ 0.688249] pci 0000:00:05.0: BAR 14: assigned [mem
0x58600000-0x586fffff]
[ 0.688253] pci 0000:01:00.0: BAR 0: assigned [mem
0x58000000-0x58003fff 64bit]
[ 0.688290] pci 0000:03:00.0: BAR 6: assigned [mem
0x58100000-0x5817ffff pref]
[ 0.688296] pci 0000:03:00.0: BAR 0: assigned [mem 0x58180000-0x58181fff]
[ 0.688303] pci 0000:03:00.0: BAR 5: assigned [mem 0x58182000-0x58183fff]
[ 0.688317] pci 0000:04:00.0: BAR 1: assigned [mem
0x1000000000-0x101fffffff 64bit pref]
[ 0.688326] pci 0000:04:00.0: BAR 0: assigned [mem 0x58200000-0x583fffff]
[ 0.688332] pci 0000:04:00.0: BAR 6: assigned [mem
0x58400000-0x584fffff pref]
[ 0.688336] pci 0000:04:00.1: BAR 0: assigned [mem 0x58500000-0x58503fff]
[ 0.688360] pci 0000:06:00.0: BAR 0: assigned [mem
0x58600000-0x58601fff 64bit]
kylin at kylin-pc:~$ dmesg | grep framebuffer
[ 1.137536] efifb: framebuffer at 0x1020000000, using 3072k, total 3072k
the efifb base address is still at 0x1020000000 after calling
pcibios_bus_to_resource().
>> results in both efi-framebuffer and amdgpudrmfb co-existing.
>>
>> The fbcon will be bound to efi-framebuffer by default and cannot be
>> used.
>>
>> [HOW]
>> Do not load efifb driver if PCI BAR has changed but not fixuped.
>> In the following cases:
>> 1. screen_info_lfb_pdev is NULL.
>> 2. __screen_info_relocation_is_valid return false.
>>
>> Signed-off-by: Shixiong Ou <oushixiong at kylinos.cn>
>> ---
>> drivers/video/fbdev/efifb.c | 4 ++++
>> drivers/video/screen_info_pci.c | 24 ++++++++++++++++++++++++
>> include/linux/screen_info.h | 5 +++++
>> 3 files changed, 33 insertions(+)
>>
>> diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
>> index 0e1bd3dba255..de8d016c9a66 100644
>> --- a/drivers/video/fbdev/efifb.c
>> +++ b/drivers/video/fbdev/efifb.c
>> @@ -303,6 +303,10 @@ static void efifb_setup(struct screen_info *si,
>> char *options)
>> static inline bool fb_base_is_valid(struct screen_info *si)
>> {
>> + /* check whether fb_base has changed but not fixuped */
>> + if (!screen_info_is_useful())
>> + return false;
>> +
>> if (si->lfb_base)
>> return true;
>> diff --git a/drivers/video/screen_info_pci.c
>> b/drivers/video/screen_info_pci.c
>> index 66bfc1d0a6dc..ac57dcaf0cac 100644
>> --- a/drivers/video/screen_info_pci.c
>> +++ b/drivers/video/screen_info_pci.c
>> @@ -9,6 +9,8 @@ static struct pci_dev *screen_info_lfb_pdev;
>> static size_t screen_info_lfb_bar;
>> static resource_size_t screen_info_lfb_res_start; // original start
>> of resource
>> static resource_size_t screen_info_lfb_offset; // framebuffer
>> offset within resource
>> +static bool screen_info_changed;
>> +static bool screen_info_fixuped;
>> static bool __screen_info_relocation_is_valid(const struct
>> screen_info *si, struct resource *pr)
>> {
>> @@ -24,6 +26,24 @@ static bool
>> __screen_info_relocation_is_valid(const struct screen_info *si, stru
>> return true;
>> }
>> +bool screen_info_is_useful(void)
>> +{
>> + unsigned int type;
>> + const struct screen_info *si = &screen_info;
>> +
>> + type = screen_info_video_type(si);
>> + if (type != VIDEO_TYPE_EFI)
>> + return true;
>> +
>> + if (screen_info_changed && !screen_info_fixuped) {
>> + pr_warn("The screen_info has changed but not fixuped");
>> + return false;
>> + }
>> +
>> + pr_info("The screen_info is useful");
>> + return true;
>> +}
>> +
>> void screen_info_apply_fixups(void)
>> {
>> struct screen_info *si = &screen_info;
>> @@ -32,18 +52,22 @@ void screen_info_apply_fixups(void)
>> struct resource *pr =
>> &screen_info_lfb_pdev->resource[screen_info_lfb_bar];
>> if (pr->start != screen_info_lfb_res_start) {
>> + screen_info_changed = true;
>> if (__screen_info_relocation_is_valid(si, pr)) {
>> /*
>> * Only update base if we have an actual
>> * relocation to a valid I/O range.
>> */
>> __screen_info_set_lfb_base(si, pr->start +
>> screen_info_lfb_offset);
>> + screen_info_fixuped = true;
>> pr_info("Relocating firmware framebuffer to offset
>> %pa[d] within %pr\n",
>> &screen_info_lfb_offset, pr);
>> } else {
>> pr_warn("Invalid relocating, disabling firmware
>> framebuffer\n");
And should something be done after __screen_info_relocation_is_valid()
return false?
Best regards
Shixiong.
>> }
>> }
>> + } else {
>> + screen_info_changed = true;
>> }
>> }
>> diff --git a/include/linux/screen_info.h b/include/linux/screen_info.h
>> index 923d68e07679..632cdbb1adbe 100644
>> --- a/include/linux/screen_info.h
>> +++ b/include/linux/screen_info.h
>> @@ -138,9 +138,14 @@ ssize_t screen_info_resources(const struct
>> screen_info *si, struct resource *r,
>> u32 __screen_info_lfb_bits_per_pixel(const struct screen_info *si);
>> #if defined(CONFIG_PCI)
>> +bool screen_info_is_useful(void);
>> void screen_info_apply_fixups(void);
>> struct pci_dev *screen_info_pci_dev(const struct screen_info *si);
>> #else
>> +bool screen_info_is_useful(void)
>> +{
>> + return true;
>> +}
>> static inline void screen_info_apply_fixups(void)
>> { }
>> static inline struct pci_dev *screen_info_pci_dev(const struct
>> screen_info *si)
>
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