Fwd: [PATCH] BGRT: Don't ioremap if image address is in System RAM (was: Re: BGRT Pointer in System RAM)
On Jul 16, 2013 6:55 PM, "Andy Lutomirski" wrote: > > Ok, so I played around with it a bit and the following patch works > > fine on my system. (I.E. image size is reasonable, cat > > /sys/firmware/acpi/bgrt/image > img.bmp generates a valid, > > non-distorted bitmap, which it did before too, btw as despite of the > > ioremap WARN_ON the ioremap seems to succeed if !(is_ram && > > pfn_valid(pfn) && !PageReserved.) > > > > How reliable is this? That is, is there any guarantee that nothing > will have overwritten the image in memory before this code runs? > >From the little digging I did, this code runs fairly early in the boot process, right after ACPI acquires all tables. If I am not mistaken it runs as part of efi_late_init which should be before efi_free_boot_services() is called. Image address on my system is B2E1B018. At boot EFI prints the following - [0.00] efi: mem23: type=4, attr=0xf, range=[0xb2c34000-0xb2e5d0 Type=4, again if I am not mistaken is EFI_BOOT_SERVICES_DATA. So all put together I think it should be reliable to read off of that address when efi-bgrt-init runs, which is before the boot services code and data are discarded. Parag -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Fwd: [PATCH] BGRT: Don't ioremap if image address is in System RAM (was: Re: BGRT Pointer in System RAM)
On Jul 16, 2013 6:55 PM, Andy Lutomirski l...@amacapital.net wrote: Ok, so I played around with it a bit and the following patch works fine on my system. (I.E. image size is reasonable, cat /sys/firmware/acpi/bgrt/image img.bmp generates a valid, non-distorted bitmap, which it did before too, btw as despite of the ioremap WARN_ON the ioremap seems to succeed if !(is_ram pfn_valid(pfn) !PageReserved.) How reliable is this? That is, is there any guarantee that nothing will have overwritten the image in memory before this code runs? From the little digging I did, this code runs fairly early in the boot process, right after ACPI acquires all tables. If I am not mistaken it runs as part of efi_late_init which should be before efi_free_boot_services() is called. Image address on my system is B2E1B018. At boot EFI prints the following - [0.00] efi: mem23: type=4, attr=0xf, range=[0xb2c34000-0xb2e5d0 Type=4, again if I am not mistaken is EFI_BOOT_SERVICES_DATA. So all put together I think it should be reliable to read off of that address when efi-bgrt-init runs, which is before the boot services code and data are discarded. Parag -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
