[PATCH] fbdev: efifb: do not load efifb if PCI BAR has changed but not fixuped
Shixiong Ou
oushixiong1025 at 163.com
Fri Jun 27 08:48:34 UTC 2025
在 2025/6/27 16:12, Thomas Zimmermann 写道:
> Hi
>
> Am 27.06.25 um 10:07 schrieb Shixiong Ou:
>>
>> 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.
>
> The patch's final revision had a rough development. Just for testing
> purposes, could you revert the commit and instead apply the patch's
> earlier revision from
>
> https://patchwork.freedesktop.org/patch/649527/?series=148057&rev=1
>
> ?
>
> Thanks a lot.
>
> Best regards
> Thomas
>
I have revert the commit and applied this patch, and added some prints as:
+ printk("pcibios_bus_to_resource orginal: start = %llx,
end = %llx",
+ r->start, r->end);
+ pcibios_bus_to_resource(pdev->bus, r, &bus_region);
+ printk("pcibios_bus_to_resource finished: start = %llx,
end = %llx",
+ r->start, r->end);
+
and the kernel message as follow:
kylin at kylin-pc:~$ dmesg | grep pcibios_bus_to_resource
[ 0.684698] pcibios_bus_to_resource orginal: start = 1020000000, end
= 10202fffff
[ 0.684702] pcibios_bus_to_resource finished: start = 1020000000, end
= 10202fffff
The address doesn't seem to have been modified.
Best regards
Shixiong.
>>
>> 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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