On Wed, Mar 12, 2025 at 10:06:15PM +0530, Avnish Chouhan wrote:
> Change RMA size from 512 MB to 768 MB which will result
> in more memory at boot time for PowerPC. When vTPM, Secure Boot or
> FADump are enabled on PowerPC, the 512 MB RMA memory is not sufficient for
> booting. With this 512 MB RMA, GRUB2 runs out of memory and fails to
> boot the machine. Sometimes even usage of CDROM requires more memory
> for installation and along with the options mentioned above exhausts
> the boot memory which results in boot failures. Increasing the RMA size
> will resolves multiple out of memory issues observed in PowerPC.
>
> Failure details (GRUB2 debugs):
>
> kern/ieee1275/init.c:550: mm requested region of size 8513000, flags 1
> kern/ieee1275/init.c:563: Cannot satisfy allocation and retain minimum
> runtime space
> kern/ieee1275/init.c:550: mm requested region of size 8513000, flags 0
> kern/ieee1275/init.c:563: Cannot satisfy allocation and retain minimum
> runtime space
> kern/file.c:215: Closing `/ppc/ppc64/initrd.img' ...
> kern/disk.c:297: Closing
> `ieee1275//vdevice/v-scsi@30000067/disk@8300000000000000'...
> kern/disk.c:311: Closing
> `ieee1275//vdevice/v-scsi@30000067/disk@8300000000000000' succeeded.
> kern/file.c:225: Closing `/ppc/ppc64/initrd.img' failed with 3.
> kern/file.c:148: Opening `/ppc/ppc64/initrd.img' succeeded.
> error: ../../grub-core/kern/mm.c:552:out of memory.
>
> Signed-off-by: Avnish Chouhan <avn...@linux.ibm.com>
> ---
> grub-core/kern/ieee1275/init.c | 44
> ++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 40 insertions(+), 4 deletions(-)
>
> diff --git a/grub-core/kern/ieee1275/init.c b/grub-core/kern/ieee1275/init.c
> index dfbd0b8..aa3c932 100644
> --- a/grub-core/kern/ieee1275/init.c
> +++ b/grub-core/kern/ieee1275/init.c
> @@ -852,7 +852,7 @@ grub_ieee1275_ibm_cas (void)
The function is preceded by a comment which is not correct after this patch.
> .vec1 = 0x80, /* ignore */
> .vec2_size = 1 + sizeof (struct option_vector2) - 2,
> .vec2 = {
> - 0, 0, -1, -1, -1, -1, -1, 512, -1, 0, 48
> + 0, 0, -1, -1, -1, -1, -1, 768, -1, 0, 48
> },
> .vec3_size = 2 - 1,
> .vec3 = 0x00e0, /* ask for FP + VMX + DFP but don't halt if unsatisfied
> */
> @@ -889,6 +889,10 @@ grub_claim_heap (void)
> {
> grub_err_t err;
> grub_uint32_t total = HEAP_MAX_SIZE;
> +#if defined(__powerpc__)
> + grub_uint32_t ibm_ca_support_reboot = 0;
> + grub_ssize_t actual;
> +#endif
>
> err = grub_ieee1275_total_mem (&rmo_top);
>
> @@ -901,11 +905,43 @@ grub_claim_heap (void)
> grub_mm_add_region_fn = grub_ieee1275_mm_add_region;
>
> #if defined(__powerpc__)
> + /* Check if it's a CAS reboot with below property. If so, we will skip CAS
> call */
> + if (grub_ieee1275_get_integer_property (grub_ieee1275_chosen,
> +
> "ibm,client-architecture-support-reboot",
> + &ibm_ca_support_reboot,
> + sizeof (ibm_ca_support_reboot),
> + &actual) >= 0)
> + grub_dprintf ("ieee1275", "ibm,client-architecture-support-reboot: %u\n",
Even if "%u" is correct please use PRIuGRUB_UINT32_T instead.
> + ibm_ca_support_reboot);
> +
> if (grub_ieee1275_test_flag
> (GRUB_IEEE1275_FLAG_CAN_TRY_CAS_FOR_MORE_MEMORY))
> {
> - /* if we have an error, don't call CAS, just hope for the best */
> - if (err == GRUB_ERR_NONE && rmo_top < (512 * 1024 * 1024))
> - grub_ieee1275_ibm_cas ();
> + /*
> + * If we have an error, don't call CAS. Just hope for the best.
> + * Along with the above, if the rmo_top is 512 MB or above. We
> + * will skip the CAS call. However, if we call CAS, the rmo_top
> + * will be set to 768 MB via CAS Vector2. But we need to call
> + * CAS with "rmo_top < 512 MB" to avoid the issue on the older
> + * Linux kernel, which still uses rmo_top as 512 MB. If we call
> + * CAS with a condition "rmo_top < 768 MB", it will result in an
> + * issue due to the IBM CAS reboot feature and we won't be able
> + * to boot the newer kernel. Whenever a reboot is detected as
> + * the CAS reboot by GRUB. It will boot the machine with the
> + * last booted kernel by reading the variable "boot-last-label"
> + * which has the info related to the last boot and it's specific
> + * to IBM PowerPC. Due to this, the machine will boot with the
> + * last booted kernel which has rmo_top as 512 MB. Also, if the
> + * reboot is detected as a CAS reboot, the GRUB will skip the CAS
> + * call. As the CAS has already been called earlier, so it is
> + * not required to call CAS even if the other conditions are met.
> + * This condition will prevent a scenario where the machine will
> + * keep doing the CAS calls and change MIN_RMA from 512 to 768 to
> + * 512 to 768 and so on older kernels. Without this check, the
It is not entirely clear what changes MIN_RMA back from 768 to 512.
I think it should be explained/clarified.
> + * machine will stuck in this mentioned stage forever.
> + * IBM PAPR : https://openpower.foundation/specifications/linuxonpower/
Thank you for adding the link to the spec.
Now the commit message and comment looks much better.
Daniel
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